Remove support for manifest configuration

[Jawnnypoo]

The ability to configure the server in the manifest is a sort of relic of when the SDK was being used with Parse.com. In order to move forward with allowing for customization, as well as adding new plugins such as FCM support, I think it is best that in the 1.17.0 release we ditch the Manifest configuration. This is the best time to do it, since 1.17.0 has API breaking changes which, if users are using GCM, will require them to update their Manifest and code anyhow.

We certainly would want to make sure it is clear in the release notes that this is occurring.

[codecov]

Codecov Report

Merging #809 into master will decrease coverage by 1.11%.
The diff coverage is 100%.

@@             Coverage Diff              @@
##             master     #809      +/-   ##
============================================
- Coverage     54.57%   53.46%   -1.12%     
+ Complexity     1716     1682      -34     
============================================
  Files           124      124              
  Lines          9874     9852      -22     
  Branches       1384     1380       -4     
============================================
- Hits           5389     5267     -122     
- Misses         4042     4156     +114     
+ Partials        443      429      -14

Impacted Files	Coverage Δ	Complexity Δ
Parse/src/main/java/com/parse/Parse.java	20.83% <100%> (-27.77%)	10 <0> (-12)
Parse/src/main/java/com/parse/ParsePlugins.java	25.27% <0%> (-16.49%)	7% <0%> (-10%)
...rse/src/main/java/com/parse/ParseCommandCache.java	0% <0%> (-7.19%)	0% <0%> (-4%)
...arse/src/main/java/com/parse/ParseCorePlugins.java	55.55% <0%> (-6.12%)	45% <0%> (-2%)
.../src/main/java/com/parse/ParseEventuallyQueue.java	0% <0%> (-5.48%)	0% <0%> (-3%)
Parse/src/main/java/com/parse/FileObjectStore.java	81.57% <0%> (-5.27%)	9% <0%> (ø)
...se/src/main/java/com/parse/ParseKeyValueCache.java	43% <0%> (-2%)	14% <0%> (-2%)
...in/java/com/parse/CachedCurrentUserController.java	90.51% <0%> (-0.87%)	14% <0%> (-1%)

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[coveralls]

Coverage decreased (-1.2%) to 57.826% when pulling d087211 on Jawnnypoo:remove-manifest-config into 329ef4a on parse-community:master.

[rogerhu]

You're getting read of manifest but keeping it here?

[Jawnnypoo]

Yeah, I tried to get rid of it for the GCM module, but it turns out we need the GCM sender ID at unpredictable times, such as when the token gets refreshed. So, we would either have to keep it in the manifest, or store it in SharedPreferences or something. I think it being in the manifest as it was before is the easiest configuration. Since most should be migrating away from the GCM module anyways, I think it is okay.

[rogerhu]

Ok we need to update https://docs.parseplatform.org/android/guide/ too...