engine: root.war cleanup

- Fixed minor text issue in message, replaced 'pack'
  with the word documentation to be more consistent.
- i18ned the message so they can be translated.
- Fixed issue where the locale in the links would have
  an underscore, while the documentation would contain
  a dash. This caused the message to popup even though
  the documentation was installed. Fixed it so it no longer
  matters if the link has an underscore or dash in it,
  both will correctly determine if the language is available.
- Added DocsMissingServlet that displays branded page notifying
  the user that the documentation in their locale is missing.
- Fixed missing documentation JSP to remove references to
  documenation style sheets and links.
- When DocsServlet determines the documentation is missing it
  forwards control to the missing documentation servlet.
- Put branding theme paths in web.xml
- Added tags for common branding patterns.
- Removed 404 page from branding, as none of the messages in there
  are brand related. the messages are added to the root messages
- Removed 404 servlet as it was no longer needed.
- Added branding module to consolidate all branding related code
  into a single package, allowing it to be easily shared between
  applications.
- Added PageNotFoundForwardServlet to allow other applications to
  forward their 404 to the root 404 handler.

Change-Id: Iceae0ebf671efc951522c464db1a5b2b95dd5637
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1011430
Bug-Url: https://bugzilla.redhat.com/show_bug.cgi?id=1010743
Signed-off-by: Alexander Wels <awels@redhat.com>