Build source tarballs for javascript projects and publish them to the
per-project location on tarballs.openstack.org.
Change-Id: Ie04995f6bd6be260bd1240f273b8dc6efb5e9188
Depends-On: I20b4b4ce0bdf03c5585ca73471611178c94e2599
Depends-On: Ib361ee2880be77eff3ef905726b032777d0b807a
