[Swift3] allow POST with both body and query parameters

[tomekc]

PR checklist

• Read the contribution guildelines.
• Ran the shell/batch script under ./bin/ to update Petstore sample so that CIs can verify the change. (For instance, only need to run ./bin/{LANG}-petstore.sh and ./bin/security/{LANG}-petstore.sh if updating the {LANG} (e.g. php, ruby, python, etc) code generator or {LANG} client's mustache templates)
• Filed the PR against the correct branch: master for non-breaking changes and 2.3.0 branch for breaking (non-backward compatible) changes.

Description of the PR

Made POST requests allow use query parameters, besides of body. Currently generated code ignores all query parameters when body exists.

Reported in #2557 and also in #2483

Note
This is a workaround of flawed Alamofire API which is actual limitation. Next time I will post a Alamofire-less template :)

[tomekc]

Interesting, check failed for seemingly unrelated reason:

[INFO]                                                                         
[INFO] ------------------------------------------------------------------------
[INFO] Building TS Fetch Default Petstore Client 1.0-SNAPSHOT
[INFO] ------------------------------------------------------------------------
[INFO] 
[INFO] --- maven-dependency-plugin:2.8:copy-dependencies (default) @ TypeScriptAngularBuildPestoreClientTests ---
[INFO] 
[INFO] --- exec-maven-plugin:1.2.1:exec (npm-install) @ TypeScriptAngularBuildPestoreClientTests ---
npm WARN package.json typescript-fetch-api@0.0.0 No repository field.
npm ERR! Linux 4.4.0-51-generic
npm ERR! argv "/home/travis/.nvm/versions/node/v4.1.2/bin/node" "/home/travis/.nvm/versions/node/v4.1.2/bin/npm" "install"
npm ERR! node v4.1.2
npm ERR! npm  v2.14.4
npm ERR! code ECONNRESET
npm ERR! errno ECONNRESET
npm ERR! syscall read
npm ERR! network read ECONNRESET
npm ERR! network This is most likely not a problem with npm itself
npm ERR! network and is related to network connectivity.
npm ERR! network In most cases you are behind a proxy or have bad network settings.
npm ERR! network 
npm ERR! network If you are behind a proxy, please make sure that the
npm ERR! network 'proxy' config is set properly.  See: 'npm help config'

[wing328]

@tomekc thanks for the PR. The test result looks good:

** TEST SUCCEEDED **

Test Suite 'All tests' started at 2017-01-06 21:42:28.060
Test Suite 'SwaggerClientTests.xctest' started at 2017-01-06 21:42:28.061
Test Suite 'PetAPITests' started at 2017-01-06 21:42:28.062
Test Case '-[SwaggerClientTests.PetAPITests test1CreatePet]' started.
Test Case '-[SwaggerClientTests.PetAPITests test1CreatePet]' passed (0.882 seconds).
Test Case '-[SwaggerClientTests.PetAPITests test2GetPet]' started.
Test Case '-[SwaggerClientTests.PetAPITests test2GetPet]' passed (0.497 seconds).
Test Case '-[SwaggerClientTests.PetAPITests test3DeletePet]' started.
Test Case '-[SwaggerClientTests.PetAPITests test3DeletePet]' passed (0.459 seconds).
Test Suite 'PetAPITests' passed at 2017-01-06 21:42:29.902.
	 Executed 3 tests, with 0 failures (0 unexpected) in 1.837 (1.841) seconds
Test Suite 'StoreAPITests' started at 2017-01-06 21:42:29.903
Test Case '-[SwaggerClientTests.StoreAPITests test1PlaceOrder]' started.
Test Case '-[SwaggerClientTests.StoreAPITests test1PlaceOrder]' passed (0.471 seconds).
Test Case '-[SwaggerClientTests.StoreAPITests test2GetOrder]' started.
Test Case '-[SwaggerClientTests.StoreAPITests test2GetOrder]' passed (0.465 seconds).
Test Case '-[SwaggerClientTests.StoreAPITests test3DeleteOrder]' started.
Test Case '-[SwaggerClientTests.StoreAPITests test3DeleteOrder]' passed (0.465 seconds).
Test Case '-[SwaggerClientTests.StoreAPITests testDownloadProgress]' started.
Test Case '-[SwaggerClientTests.StoreAPITests testDownloadProgress]' passed (0.469 seconds).
Test Suite 'StoreAPITests' passed at 2017-01-06 21:42:31.778.
	 Executed 4 tests, with 0 failures (0 unexpected) in 1.870 (1.875) seconds
Test Suite 'UserAPITests' started at 2017-01-06 21:42:31.780
Test Case '-[SwaggerClientTests.UserAPITests test1CreateUser]' started.
Test Case '-[SwaggerClientTests.UserAPITests test1CreateUser]' passed (0.476 seconds).
Test Case '-[SwaggerClientTests.UserAPITests test2GetUser]' started.
Test Case '-[SwaggerClientTests.UserAPITests test2GetUser]' passed (0.465 seconds).
Test Case '-[SwaggerClientTests.UserAPITests test3DeleteUser]' started.
Test Case '-[SwaggerClientTests.UserAPITests test3DeleteUser]' passed (0.506 seconds).
Test Case '-[SwaggerClientTests.UserAPITests testLogin]' started.
Test Case '-[SwaggerClientTests.UserAPITests testLogin]' passed (0.489 seconds).
Test Case '-[SwaggerClientTests.UserAPITests testLogout]' started.
Test Case '-[SwaggerClientTests.UserAPITests testLogout]' passed (0.457 seconds).
Test Suite 'UserAPITests' passed at 2017-01-06 21:42:34.179.
	 Executed 5 tests, with 0 failures (0 unexpected) in 2.393 (2.399) seconds
Test Suite 'SwaggerClientTests.xctest' passed at 2017-01-06 21:42:34.180.
	 Executed 12 tests, with 0 failures (0 unexpected) in 6.100 (6.119) seconds
Test Suite 'All tests' passed at 2017-01-06 21:42:34.182.
	 Executed 12 tests, with 0 failures (0 unexpected) in 6.100 (6.122) seconds
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time: 01:32 min
[INFO] Finished at: 2017-01-06T21:42:34+08:00
[INFO] Final Memory: 11M/245M
[INFO] ------------------------------------------------------------------------

cc @jaz-ah @Edubits @hexelon

[jaz-ah]

+1 @wing328

[hexelon]

+1 @wing328

One thing I'd add is some scenario where a call "mapValuesToQueryItems" is generated. There's no such scenario in the current petstore.

[wing328]

@hexelon good idea. We might want to leverage the fake Petstore for the additional test case

[tomekc]

@wing328 @hexelon Speaking about tests, I have more improvements underway and found http://httpbin.org useful for testing all possible request types.