test: Respond to Github ping events

Signed-off-by: Lewis Marshall <lewis@lmars.net>
test: Shutdown cluster if Flynn build fails

Signed-off-by: Lewis Marshall <lewis@lmars.net>
test: Fetch Github PR commits

Signed-off-by: Lewis Marshall <lewis@lmars.net>
test: Fail PR builds which don't merge into master

Signed-off-by: Lewis Marshall <lewis@lmars.net>
Merge pull request #116 from flynn/test-pull-request-updates

Test pull request updates