[RFR] - REFS #143 - use BackBee/Utils inside BackBee

* Applied php-cs-fixer
* Removed unused classes (which have been moved to ``utils`` library
* Use ``utils`` library inside project, updated namespaces and composer.json
I am used to apply `php-formatter` at the end, but in my case (I think because I have an old `php-cs-fixer` version) the `php-cs-fixer` does not remove this line :S

Just place the php-formatter work at the end :dancer: