Upgrade ABTT to work on rails 2.3.14

This is a work-in-progress, but it's enough to log in and view the
home-page (and some others).
Remove all calls to render_partial

These are easily converted to render :partial => 'foo'
Fix render :partial with :locals call

The keys in the hash passed to :locals should be symbols, not strings.
This fixes the only such callsite (I grepped for others).
Merge pull request #64 from nharper/rails-upgrade

Rails upgrade