Field "Volume name" on Horizon no longer mandatory

Change the field of "Volume name" on Horizon dashboard in process
of create or edit volume from mandatory to optional.
This is supported by the fact that Horizon dashboard displays the
volume's ID for the volume's name if its name is None or empty.

Change-Id: Ic8e6f8d3ffe51a4c2faf9ca636215e6e24f435b4
Closes-Bug: #1389172
'Session timed out' error on 'Login' sceen doesn't have proper css

The 'Session timed out' error message should have proper help-block
and alert-danger message css in order to be consistent with other
portal messages.

Change-Id: I1ea5c17f70df29225d79aac28658eb3f6df0a5e7
Closes-Bug: 1369816
Merge "'Session timed out' error on 'Login' sceen doesn't have proper css"
Merge "Field "Volume name" on Horizon no longer mandatory"