Themes Blue/Original and Green

- Included new theme called "Green".

- Renamed existing css files (itdb.css and theme.css) to include the
theme name (itdb.blue.css and theme.blue.css). Hope the rename action
does not cause other problem, but since everthing else looked quite
normal and I couldn't find any page where it came to problem, I guess
it's okay. If there are problems I suggest that the new way / reference
to the css files (by querying the database to determine the theme part
in the css file name) should be used.

- Added a query to get theme name from database (e.g. "blue") and this
determines which css file is used (blue or green) in the header.php

- Updated settings.php to include new theme option.