Fixes some column translations

add more entries to "display_choices" of "Status", "Power" and
"Task" column, in order to get the states translated.

Closes-Bug: #1224329
Change-Id: I22ee666678c8bce24c2d6c696438b481006bd609
Group specific fields in horizon.form module

    According to the Django architecture, all fields are grouped in
the django.form module, Horizon fields were dispatched in two modules
utils and form. This patch cleanup the loading of Horizon specific
fields.

Change-Id: Ib18848a8cc06dbd5984ec02d7cd647145124ced4
Closes-Bug: #1287634
Merge "Fixes some column translations"
Merge "Group specific fields in horizon.form module"