Merge pull request #6 from loldev/develop

Pull
Added peek mode
Added getQueueId
Remove unnecessary $_queues array from AbstractAdapter and from Mongo
Fixed loldev/ZendQueue#36 
Fixed comments
renamed isQueueExist to queueExists
Develop
Fixed handle
Added Db Adapter repeatingInterval
Added Db Adapter peekMode
Removed listQueues from single queue instance context
Added unschedule feature
cleanup tests
Merge pull request #76 from leonardograsso/develop

Close loldev/ZendQueue#60
Close loldev/ZendQueue#61
Close loldev/ZendQueue#72
Close loldev/ZendQueue#36