Add xstatic-packaged JavaScript libraries for Horizon

Those libraries are removed from Horizon's static directory, and
packaged separately for easier maintenance and versioning.

They package sources are going to be hosted on StackForge, see
patch https://review.openstack.org/#/c/95716/

Change-Id: I3efd9527d9be8c263458d0531f7a4c9c49d75d01
Partially-implements: blueprint remove-javascript-bundling
Merge "Add xstatic-packaged JavaScript libraries for Horizon"