implemented the retrieval of queue - agent association
implemented agent-queue association edition
implemented sysconfd and rabbitmq notification
fixed exceptions parameters
fixed mistakes in imports
fixed indentation
using proper imports and proper assertions
moved QueueNotExistsError to a queues package
using a DBConverter for QueueMembers
specific exception raised when the agent of an agent-queue association does not exist
fixed queue member validator : agent_dao.get is returning None, not raising an exception
Merge branch 'agent_penalties'