Added the optional use of doc pull in gate deployment scripts. When the
remote_work_dir is defined, the new pull doc role will invoke airshipctl
document pull command to download the manifests to the remote_work_dir.
This role is not included in zuul job so the zuul job will continue to use
the already checked out manifests in the zuul.project.src directory.
Fixes #112
Change-Id: I754c08661ad0b635819cb3730e05a6986d90f5ca
Signed-off-by: James Gu <james.gu@att.com>
d26df73b4b