Improve the admin configuration form usability

I have some ideas on how the admin UI can be improved for better usability. Please take a look and let me know if you like the changes and would consider pulling them into the module.

The changes this patch provide are:

1) Title-capped mode and description strings.
2) Use radio buttons that contain descriptions inline with the selection instead of a select widget.
3) Added the current mode to the title of each role fieldset (for easier overview of your current settings).
4) Display the "Data" and "Path" widgets only if the required mode is selected.

(patch coming)