allocator: Retry failed allocations immediately upon a deallocation
allocator: Retry failed allocations immediately upon a deallocation

We retry failed allocations every 5 minutes. If something else gets
deallocated, we should trigger the retry immediately in case the
allocations were failing due to IP exhaustion, and the deallocation
freed up an IP.

Signed-off-by: Aaron Lehmann <8ecfc6017a87905413dcd7d63696a2a4c351b604@docker.com>

docker/swarmkit,alyyousuf7/swarmkit,RenaudWasTaken/swarmkit,cheyang/swarmkit,jlhawn/swarmkit,alyyousuf7/swarmkit,Noyan759/swarmkit,jlhawn/swarmkit,Noyan759/swarmkit,AliyunContainerService/swarmkit,dperny/swarmkit-1,dperny/swarmkit-1,sungwonh/swarmkit,AliyunContainerService/swarmkit,docker/swarmkit,RenaudWasTaken/swarmkit,cheyang/swarmkit,sungwonh/swarmkit,diogomonica/swarmkit,diogomonica/swarmkit