Merge pull request RichardKnop#199 from RichardKnop/feature/add-async…

…-worker-launch-method

Add a non blocking LaunchAsync method to worker

First Ctrl+C starts graceful shutdown. Second Ctrl+C abruptly ends th…

…e program.

Merge pull request RichardKnop#195 from RichardKnop/feature/wait-for-…

…running-tasks-to-finish-before-quitting

Wait for running tasks to finish when quitting a worker.

Updated dep cli tool and ran dep ensure -update

Updated Makefile

Pruned dependencies.

Fixed goling issues.

Merge pull request RichardKnop#174 from xitongsys/master

fix err chan size in server.go

Merge pull request RichardKnop#173 from RichardKnop/feature/fix-send-…

…group-concurrency

Fix pool logic to handle concurrency in SendGroup call.

When using AMQP as backend, set x-expires parameter so task state que…

…ues will eventually be cleaned up.