Merge pull request #20 from KnpLabs/feature/SoftDeletable/PostDelete

Add a post delete feature to the SoftDeletable trait
Add new SoftDeletable feature to README.md
Remove useless doc
add License; close #22
Fixed removal of translations.

Removed translations weren't actually removed from the database, added orphanRemoval=true to fix this.
Merge pull request #24 from jankramer/fix-translation-removal

Fixed removal of translations
Add a method to test the removal of the object in the future