worker deregistration and graceful shutdown
tests for complicated deregistration
adding drone.yml
need gearmand service, of course
Only restart gearmand if we are not drone

Since drone is running gearmand in a container, it is difficult to
restart the process. We also don't have to worry about residual
jobs from dev or tests, etc in drone.
need to 'make' first before test
test on worker error, combined redundant tests
Merge pull request #10 from Clever/worker-shutdown

worker deregister