Migrate RequestContext users to render() calls.

This was necessary because render_to_response no longer takes a
context_instance. We were always using this to pass in a RequestContext,
which the render shortcut can already do, so switch to that.

Remove noop conservancy.context_processors imports.

You'll note this source doesn't exist in Git.
There's a reason for that.

Add sitefundgoal to top level view context.

The base template now has access to the fund-raising goal that will be
displayed site-wide. The view here must provide it in the context for
access everywhere.

Furthermore, we need a local context processor to make sure it's in
context everywhere, and we have to make sure that context is properly
passed along.

This code is a bit cargo-culted in, based on what I read in various
places about adding the Request context.

Ordering likely screwed up when I muck with query.

Force order_by at the end of my mucking.

Place Supporters counter on front & sponsors pages

The number of current supporters now appears on the frontpage and the
sponsors page.

Support anonymous supporter listings by count.

Remove anonymous listing from the alphabetical supporters list and
instead list them by count found.

Supporters list built dynamically.

Hitherto the supporters list has been committed directly to the static
sponsors/index.html file. This was never ideal and a quick hack to
build Conservancy's supporters list at the beginning of the supporters
program.

With this change, a Django app now exists that dynamically generates the
supporters list.

The database rows must be built from Conservancy's internal Ledger file,
which will be done in a separate script.