implement a very simple, wxpython based, config wizard

implement a very simple, wxpython based, config wizard

This implements a very small app using a wx ui to log a user in.

it takes a username and password, and submits them to a backend on the web site
(currently the allmydata test net webserver) to authenticate them.  It returns
the 'root_cap' uri of the user's virtual drive. Also the introducer.furl is
retrieved.  These are then written into the default noderoot basedir in their
usual files (private/root_dir.cap and introducer.furl)

a button is provided which will direct the user to the web site in the event
that they need to register in order to have an account to use.

once the user is successfully authenticated and the files are written, then
on win32 the tahoe service will be started.