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.

Just quit it with this relative import stuff.

While I think these relative imports seem to be valid for the running
application, I am having trouble with the django-admin applications
regarding them. I don't see this syntactic sugar as absolutely
essential, so I'm just going to change it now.

Adapted Django application stuff for Conservancy; and normalized to string
"conservancy" within code and templates.