Add sensu::check for pp-smokey tests in Jenkins

The checker script is run with a pp-smokey test name, ie `backdrop_read`. It
downloads the latest pp-smokey results from Jenkins and parses the output.
It returns an exit code which a Sensu check can interpret (ie 0 is OK, 3
is CRITICAL)

The checks run on the monitoring box and invoke the smoke test checker script
every minute.

https://www.pivotaltracker.com/story/show/67409248

[Delivers #67409248]