Paralellize tests with debian/rules

Change-Id: Ib561374aef3948920a904f8fe1995162ce7b48c6
Reviewed-on: http://review.couchbase.org/43092
Tested-by: Mark Nunberg <mnunberg@haskalah.org>
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>