Added tests for copy() method
FOFTable: Fixed bug when calling the copy function with an integer, not an array
          Fixed bug on slug generation
Merge branch 'feature/tests' of git@github.com:akeeba/fof.git into feature/tests
FOFTable: fixed warning on check method
Added new annotation to prevent data loading, in order to speed up Database based tests
Merge remote-tracking branch 'github/feature/tests' into development