Associate an agent to a queue

Notify the cti server
Merge branch 'master' into create_agent_queue_association
Notify xivo bus
Notify agent bus on agent queue association
Raise error on agent queue not found associate

Fix validation for queue agent association edition
Raise error if agent already associated
Remove agent queue association
Notify bus on agent removed from queue
add an accessor to retrieve the dao session in db_utils
Merge branch 'create_agent_queue_association' of https://github.com/jlebleu/xivo-dao into jlebleu-create_agent_queue_association
remove a debug line
remove commented blank line
minor style fix

use scalar() instead of first()[0]
remove camelCase
remove parens in the if
white spaces
Merge branch 'jlebleu-create_agent_queue_association'
notifier has 2 arguments
Merge branch 'master' into session-interface-cleanup

Conflicts:
	xivo_dao/data_handler/queue_members/dao.py
	xivo_dao/helpers/db_utils.py