#2 Add ability to use Google Adsense

[Matthew Smalley]

Allow the config to include, in the thumbnails page,
Google ads.

The option to do this should be in the main config (ie
on the GUI screen), and the ads should appear as a
column at the right hand side of the thumbnails page.
All necessary information for Google adsense should be
passed into picweb via the main config GUI.