Update commit validation to not use cmake/ prefix

Change-Id: If4f0c159b07feaa1b5cda27491db192fefcccce5
Reviewed-on: http://review.couchbase.org/35360
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>