qt-jenkins-deploy: do not require gerrit_host by default, new vars
qt-jenkins-deploy: do not require gerrit_host by default, new vars

Do not require gerrit_host by default.
Added three new variables:
- artifacts_download_url : url for downloading (build) artifacts (http://server.com)
- artifacts_upload_host : host for (build) artifacts (user@server.com)
- artifacts_upload_path : base path to use on host machine (/my/path/)

Change-Id: I6e93eba4dbc5d19a633973001d14e79ec5b5c9cd
Reviewed-by: Janne Anttila <237e68234a327a5775cffcea05af0474ad4190b9@digia.com>

tsarajar/qtqa,tsarajar/qtqa,tsarajar/qtqa,tsarajar/qtqa