Add CONTRIBUTING file.

Change-Id: Idadfda08c42b40411bb38813bd5996515ea5b491
Migrate test base class to testtools.

This is stricter, but also provides plumbing for more advanced things
like fixtures and testscenarios.

Change-Id: I607b50390708ca3caa9799ef0b27007df5045a6c
Use a task to delete Instances

Change-Id: Ic8c5552c52c0c00ef081a87525cd3b0bb011ce20
Remove eventlet dependency from unit tests

Unit tests should not need to know about eventlet. Instead of stubbing
eventlet.sleep(), stub out the TaskRunner._sleep() method in the scheduler.

Change-Id: I438a5d6978ed228d62a0d28fef30115d205bd2c3
Merge "Add CONTRIBUTING file."
Merge "Migrate test base class to testtools."