refactor sqlalchemy models
refactor sqlalchemy models
refactor func key tests. make prerequisites generic
implement func keys with a queue destination
remove unused imports
Merge branch 'relationship' of github.com:xivo-pbx/xivo-dao into relationship

* 'relationship' of github.com:xivo-pbx/xivo-dao:
  refactor sqlalchemy models

Conflicts:
	xivo_dao/alchemy/linefeatures.py
	xivo_dao/data_handler/extension/tests/test_dao.py
	xivo_dao/data_handler/func_key/tests/test_dao.py
	xivo_dao/data_handler/voicemail/tests/test_dao.py
Merge branch 'relationship'