Minor cleanups on FWaaS message strings

Closes-Bugs: #1224839

- Remove a trailing colon for better consistency of the item names
  in FWaaS rule detail.
- Add a missing space in the message in FWaaS policy creation form.

Change-Id: Ie09a9266831064f0c4b588f8abfd799dfeeb3a33
Merge "Minor cleanups on FWaaS message strings"