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
'Stack Template' tab for Heat Stack Details page

Once you launch a stack from any template source (using raw data
or template file), there is no possibility to check this template
later from Horizon. This patch set adds 'Stack Template' tab to
Stack Details page.

Partially implements blueprint: heat-ui-improvement

Change-Id: I27fb687829f9c060ea55d81bcc0344a6e782da06
Merge "'Session timed out' error on 'Login' sceen doesn't have proper css"
Merge "Field "Volume name" on Horizon no longer mandatory"