Static pages (with rough layouts and placeholder text), and related changes.

NOTE: This also includes an overhaul of the routing logic, including a new ```SITE.routes.py``` file that should be copied into the __main web2py directory__ as ```web2py/routes.py```

There are also some new controllers (about, subtrees, contact) and corresponding views for the static pages. Edit the HTML files in the ```views``` subfolders to make changes.

Oh, and I removed the plugin_wiki plugin, which cleared out lots of unused files.