WorkerQueue doesn't flush on exit

[spenthil]

The following won't report anything when run as a script, but it will work when from REPL:

import errplane
_errplane = errplane.Errplane("errplane_api_key", "errplane_application_id")
_errplane.report("problem")

Seems like WorkerQueue doesn't get flushed before exit because it uses daemonized worker threads.

Cleanest solution in my mind is adding Errplane.flush that blocks.

[toddboom]

Excellent idea. We'll get that added in there this week.