Add .travis.yml

Change-Id: I1496451afac2865943730a2c98062e1e884f6645
Reviewed-on: http://review.couchbase.org/26757
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Mordechai Nunberg <mnunberg@haskalah.org>