Add check on coding standard

[mavimo]

Add CI step to ensure coding standard, some CS we should evaluate:

• [ ] https://github.com/consistence/coding-standard
• [ ] https://github.com/slevomat/coding-standard
• [ ] https://github.com/djoos/Symfony-coding-standard

I'll add on version 0.8 since most of them do not support php 5.6 as we do on 0.7

[ste93cry]

Since this has been done in #94 I believe you can close this issue