Fix endpoint error when running keystone on apache

When running keystone in httpd, horizon could not generate the
right keystone endpoint url. Fixes this issue by retrieving the
whole path from the service_catalog or OPENSTACK_KEYSTONE_URL
and generating a new url.

Change-Id: Id8459947498127e47700d9f690d4ed4d5cadbba9
Closes-bug: #1295128
Update documentation to clarify Image Upload setting

The documentation at http://docs.openstack.org/developer/horizon/topics
/deployment.html#file-uploads states that the end user should change the
setting "HORIZON_IMAGES_ALLOW_UPLOAD = False" to disable image uploads.

This suggests that image uploads will be completely disabled, however it
will still be possible to upload images via URL.

This change adds this clarification to the documentation.

Closes-Bug: 1215921
Change-Id: Ie1cc51aaf459f9eb2881121b405fb16e762e265b
Merge "Fix endpoint error when running keystone on apache"
Merge "Update documentation to clarify Image Upload setting"