Add new meta component.

This component, right now, only have the trait and the interface, placed before in the Product component
Product component has now this new component as a requirement
Fixed travis files

* Reduced the matrix size. Just check for SF2.4
* Fixed indentation
* phpunit script is executed without -c
Removed phpunit from dependencies.
Fixed some minor typo
Merge pull request #257 from elcodi/feature/meta-component

Add new meta component.