Fixes bad performance when editing project members

The bug is caused by consecutive client calls when
fetching users' roles in a project.

The fix was to use the /v3/role_assignments endpoint.
Which retrieves all roles in a single client call
(dashboards/admin/projects/workflows.py:
UpdateProjectGroupsAction and UpdateProjectUsersAction).

The compatibility to the previous keystoneclient version
is maintained.

In a scenario with 1000 users with a role in a project
(using devstack), the time to render the Modify Users
page dropped from 45s to 2.5s

Change-Id: Ic72ebea0db226faf98c5e04d00d76dedd1fb01c1
Closes-bug: #1278920
AttributeError at attaching a non-existent volume

When user tries to attach a non-existent volume, AttributeError
exception is thrown in get_data function, where the right behavior
is returning [].

This patch is based in the solution proposed by Matthew D. Wood.

Change-Id: Ib6c5f83845e0056865a8ace82d9e2f4351d4be3e
Closes-Bug: #1288419
Rename Host to Allowed Host

To avoid confusion between nova hosts and
database user host e.g. as used in a grant
statement we will rename that one to
'Allowed Host'

Updated launch dialog and users table to
use 'Allowed Host' consistently.
Updated launch dialog help text to clean
up some of the descriptions

Change-Id: Ice39cd6712eb757a4d0f5beaedcda580fbeb4acb
Closes-Bug: #1342134
Fixing data processing image registry

The Data Processing Image Registry was not adapted to use
expect the "previous" return value from glance.image_list_detailed.
This change allows the Image Registry to work correctly again.

Change-Id: I990962483197f54ee9436278463c4709b909297a
Closes-Bug:  #1347036
Merge "AttributeError at attaching a non-existent volume"
Merge "Rename Host to Allowed Host"
Imported Translations from Transifex

Change-Id: I0c57cf6a920d33ad40c712cb13fbb1890702d58d
Merge "Fixing data processing image registry"
Merge "Fixes bad performance when editing project members"