We're moving towards out-of-source builds

Change-Id: I8a9184f835eec95e258da1f2583fcf907032ce05
Reviewed-on: http://review.couchbase.org/35432
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>