Replace jshint by eslint

[elboletaire]

I'm creating the PR as a WIP because I'm currently working on it and I see things which create some questions for me:

• I get a lot of no-undef errors due to the injected libraries (under testing, the it and describe, more specifically). I've currently switch the rule to show warnings instead of errors, but I think it's better to disable it adding /* eslint no-undef: 'off' */ for each test file that brings an error. If you're ok with it, I'll do a commit re-enabling the rule and setting the rule file by file.
• I've set no-console to warn. Would you like to set it to off, or is it ok to stay as warnings?

I'll also try to edit this post to add some notes about some decisions I made:

• The first commit is just the automatically created file from eslint --init. There are a lot of rules set to off that you may want to check.
• I've set no-extra-boolean-cast to warn in order to change from errors to warnings, so you don't forget about it :p
• I've set no-empty with "allowEmptyCatch": true, to allow empty catch statements.
• As there's no option for setting the .eslintignore file as a grunt-eslint parameter, I've decided to move both .eslintrc.json and .eslintignore to the root path, and remove the tasks/support folder, which was containing the .jshintrc file.
• We should consider changing the strict rules, as they're not needed for nodejs modules (they're in strict mode by default).

refs #436

[matteofigus]

I've read your mind before so opened #449 💃

[elboletaire]

haha did not see it :p

Then I'll merge my branch with master when your PR is accepted. I remove that question from the PR, but please, try to answer the other ones too 😃

[elboletaire]

Added note:

• As there's no option for setting the .eslintignore file as a grunt-eslint parameter, I've decided to move both .eslintrc.json and .eslintignore to the root path, and remove the tasks/support folder, which was containing the .jshintrc file.

[elboletaire]

I've removed the WIP because my work is done until you answer that two questions in the PR 😃

Tests run perfect locally, but for some reason weren't executed in travis nor in appveyor.

[elboletaire]

PS. Merging with master, as #449 has been merged

[elboletaire]

Added:

• We should consider changing the strict rules, as they're not needed for nodejs modules (they're in strict mode by default).

[elboletaire]

Merged with master and fixed no-unused-vars issues appeared after enabling the rule again.

Note that I've set no-unused-vars: 'off' in registry-domain-components-cache.js because there's giving a false positive (apparently does not properly detect the scope of the response var).

[matteofigus]

This looks good to me for now. Let's create separate issues for each rule that we may want to change. Agree about the no-strict, in case let's make a different PR for that.

Thanks for working on this!