Introduce Cassandra repository.
fonctionnal cassandra implementatio (thrift)
before moving to cql
Checkstyle fix + tests

M
Refactor.

M
Move client API to bootstrap.
First step : 
* vm life cycle
* getLocalControllerList
* getGroupmanagerDescriptions (for admin view)
BootstrapBackend : remove monitoring from hierarchy.
BootstrapResource : add migrate logic
GroupManagerDatabase : add static groupmanager description to repository
BootstrapRepository : add get[lcs|gms|vms] and migrate
BootrsapCassandraRespoitory : implements BootstrapRepository
CassandraRepository : introduce the use RowIterator.

GroupManagerBackend : introduce externalSender (moved from glinit and
gminit) / manage isAssigned flag
LocalControllerBackend : manager isAssigned and localControllerLocation.

RabbitMQ : 
routing key fix in Anomaly Resolver and MigrationPlanenforcer.
add state change message (GroupManagerStateMachine)
add message GM_FAILED in LC.
fix routingKey issue.
createMigrationRequest : fix unknown vm and unknown lc issue (cassandra)
Add compute resource (vm are reachable at bootstrap/compute/$id[get,
put]) )
Checkstyle.