Adds PHP-CS-Fixer as dev dependency

https://github.com/fabpot/PHP-CS-Fixer
[travis] Update script for get php-cs-fixer from Composer install
fix for #5223

Problem with namespace
 Abstract cannot define the implementation
Merge branch 'hotfix/php-cs-fixer' of github.com:Maks3w/zf2 into Maks3w-hotfix/php-cs-fixer
Close #5281
Close #5282
Merge branch 'hotfix/5223' of github.com:ClemensSahs/zf2 into ClemensSahs-hotfix/5223
Close #5292
Merge branch 'hotfix/abstract-class-generation' of github.com:blanchonvincent/zf2 into blanchonvincent-hotfix/abstract-class-generation
Close #5296
fix wording : instantiate "class"/"interface", not instantiate "object"