Implemente gearman-type workers

[le-garff-yoann]

• less load on the main process.

[le-garff-yoann]

Could be added via an asynchronous collector based on AnyEvent::Gearman::Client.

This collector take :

• a list of collectors to manage.
• a list of IP/port (workers).

It recursively disable the managed collectors via REST and send the whole definition to the less loaded available worker.