Add simple URL endpoint for checking the Redis connection.
Better test URL for the sample Rails app.
Fix Rails tests.
Allow Redis URL config through environment variable.
Drop support for REE.
Handle Redis connection in Resque job (if different than Resque's connection).
Update README.
Don't use hiredis in JRuby.
Fix JRuby support, don't test Resque under JRuby.
Remove .ruby-version.