'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"