Merge pull request #28 from chives/dev

Added set($key, $value) method on repository
New method save() on repository, fixes issue with lack of em->flush() call
Method add() now invokes save() to avoid code duplication
Refactoring specs
Merge pull request #29 from bartekgruszka/fix-repository-set

New method save() on repository
update twig dependency
Merge pull request #30 from JarekW/dev

update twig dependency
Added fsi_image and fsi_removable_file resource types