[site] add new myfaces skin project

[simon <sk...@apache.org>]

Hi,

Currently the myfaces site "look and feel" is done by including a
site.css file in every maven module. It would be nicer to instead define
a "skin" project that myfaces modules can then just reference.

There is currently already a skin module for tobago here:
  http://svn.apache.org/repos/asf/myfaces/maven/trunk/tobago-site-skin/

Are there any objections if I create a sibling directory for
myfaces-site-skin? Unless someone speaks up I will add this tomorrow..

The initial files will be just what we are currently using, but
hopefully we can then later move to using the nice look proposed earlier
by Adonis..

Regards,

Simon