[Commit validation] Add common script for single-project build/test

Change-Id: I48b8c037f0a4c96bc603ba793daf8caf59b3280c
Reviewed-on: http://review.couchbase.org/43783
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Dave Rigby <daver@couchbase.com>