Added ability to autogenerate tests

DockerBot can now automatically try to find tests to run, based on which
files have been edited. Any file which starts with cfme/tests/ will be
run against the default provider set.
![image](https://cloud.githubusercontent.com/assets/441252/3512605/f35ad1b6-06ba-11e4-9fa3-97c7630dfe7f.png)