Move creation of bash config to install_gw.py

Change-Id: I5ebba7a8a5cfd3d358bb6f4e828b0c2428c2cb04
Reviewed-on: http://review.couchbase.org/36797
Reviewed-by: Li Yang <lichenyang2@gmail.com>
Tested-by: buildbot <build@couchbase.com>