Set the correct min_disk size when creating volume from image

Sometimes the image min_disk size is specified in a property rather
than the min_disk attribute (for instance, after creating a snapshot
from an instance). This ensures that the correct tooltip and error
message are displayed in these cases too.

Change-Id: I0c7a87a6f00c4cc1a54f8b70e5df9bb1d05de866
Closes-Bug: #1368600
(cherry picked from commit 6b62f616b1d6f7d71a34ea59ba8c8120745915f4)
Add OS_REGION_NAME to openrc

The openrc file that is downloaded from Horizon is missing the
OS_REGION_NAME setting. This causes issues in environments that have
multiple regions. If the Region is none, ensure that it is unset after
sourcing the rc file to avoid and empty variable. This fix also cleans
up some language in the generated openrc file.

Change-Id: Ieab0b13afd79158c6bf603891164f01aff3aabf3
Closes-Bug: #1334791
(cherry picked from commit a8692b7726fb43af867844950538eb5ce6436a35)
Rename add_error methods: Django 1.7 conflict

In Django 1.7, Forms have an add_error() method and our definition
was conflicting with Django's method. Thanks to hertzog@debian.org
for the patch.

Note that it is required to support Django 1.7 in Icehouse, because
we're planning to release Debian Jessie with both Django 1.7 and
Icehouse. This is to *support* Django 1.7, not at all to *switch* to
it, which is very different.

Close-bug: #1352919
Change-Id: I1f558cf7f3198a68629738a011e9cae0c3749320
(cherry picked from commit 04dd1568c1c927901085941124e4c6852183f4f0)
Merge "Rename add_error methods: Django 1.7 conflict" into stable/icehouse
Merge "Add OS_REGION_NAME to openrc" into stable/icehouse
Merge "Set the correct min_disk size when creating volume from image" into stable/icehouse