userportal,webadmin: Customized parameterized messages

- Implemented DynamicMessages to facilitate the use of
parameterized messages in branding packages.
- Renamed DynamicConstants to DynamicMessages.
- Added {0} to version about.

Change-Id: Iad253128d6bb48b0be93bb580803101b7e85bcea
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=816173
Signed-off-by: Alexander Wels <awels@redhat.com>