doc: Add DITA help pages

Kimchi's help pages will be provided in a specific XML format, DITA -
Darwin Information Typing Architecture, and they will be converted
automatically to HTML files during build time.

To build the HTML files, just type:

    $ make -C ui/pages/help

The main "Makefile" will also execute that command above.

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>
doc: Add help files to dist packages

The DITA help files should also be included in the RPM and DEB files
which will distribute Kimchi. Only the generated HTML files will be
added

Also, update the README to list the dependecies needed to convert the
DITA files to HTML.

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>
doc: Export the help pages to cherrypy

The new DITA help pages will be exported to cherrypy under the URL
"help/". For example, the help page "kimhstor.html" can be acessed in a
local Kimchi installation at "http://localhost:8000/help/kimhstor.html".

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>
doc: Ignore the generated files

As the HTML files are generated according to the DITA files, we do not
need to include them to the Git repository. They can always be regenerated
when needed.

Signed-off-by: Crístian Viana <vianac@linux.vnet.ibm.com>