userportal, webadmin: new look and feel based on PatternFly

Initial implementation of new oVirt look and feel based on PatternFly (https://www.patternfly.org/).
Includes new looks for:
 * welcome page
 * login page
 * 404 page
 * no_lang page
 * top banner of both webadmin and userportal

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Implementation notes
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 * this commit effectively brings Bootstrap3 CSS library into ovirt-engine for full use. Bootstrap
   itself is not included, but PatternFly is a skinned version of Bootstrap. All Bootstrap widgets
   are present and usable.

 * adds gwtbootstrap3 library. This library adds a bootstrap-aware rendering to GWT widgets. These
   widgets render with minimal GWT decoration (no wrapping divs, etc.) for easier hits to bootstrap
   selectors.

 * adds PatternFly (https://www.patternfly.org/) to the project. Since we are transitioning to
   PatternFly in phases, this first phase requires some hacks to be stacked on top of PatternFly.
   patternfly-custom-hacks.css includes these.

 * added a new obrand messages JSP tag for including branding messages in JSPs with no backing servlet.

Change-Id: I806f2d163d80edb632c4e87524c327066cf3377a
Signed-off-by: Greg Sheremeta <gshereme@redhat.com>