Supply full bundle path for Ruby 1.9.1

Unfortunately, we will need to supply the full path
to /usr/bin/bundle along with specifying ruby1.9.1
to get around versioning issues.

Change-Id: I7927d42a432f82156f38036557c90e3c0e2ecb7d
Reviewed-on: https://review.openstack.org/29009
Reviewed-by: Clark Boylan <clark.boylan@gmail.com>
Reviewed-by: John Dewey <john@dewey.ws>
Approved: Jeremy Stanley <fungi@yuggoth.org>
Reviewed-by: Jeremy Stanley <fungi@yuggoth.org>
Tested-by: Jenkins