[2.0] Add PHP-CS-Ffixer

[Jean85]

Q	A
Bug fix?	no
New feature?	no
BC breaks?	no
Deprecations?	no
Related tickets	#115
License	MIT

What's in this PR?

As suggested in #117 (comment), we can add PHP-CS-Fixer for better DX an stricter CS.

I'm also migrating to Travis CI jobs structure, to allow better flow in the CS (and CS/AST checks too if needed).

Example Usage

$ composer cs-check
> vendor/bin/php-cs-fixer fix --dry-run
Loaded config default from "/home/alai/workspace/OSS/client-common/.php_cs".
Using cache file ".php_cs.cache".
   1) src/Deferred.php

Checked all files in 0.029 seconds, 10.000 MB memory used
Script vendor/bin/php-cs-fixer fix --dry-run handling the cs-check event returned with error code 8

To Do

• Add Pretty CI

[dbu]

looks good to me. the settings are slightly different from php-http/boilerplate#27 - i want to be consistent on all projects. but i think the fix here is to update the rules in boilerplate.

[dbu]

and imho we should delete .styleci.yml and disable the hook after this is merged.

[Jean85]

StyleCI config removed. Let me know if I have to do anything else, or if we should add other CS rules.

I don't think I can add PrettyCI though. Should I add the CS check in Travis in the meantime?

[dbu]

no, if you have run the php-cs-fixer on the cli that is good enough. i will merge this and enable pretty-ci.

[dbu]

the settings are slightly different from php-http/boilerplate#27 - i want to be consistent on all projects. but i think the fix here is to update the rules in boilerplate.

php-http/boilerplate#28

[dbu]

disabled styleci and enabled prettyci