Added support for connection_ref's down throughout

the code, so models can connect to specific Redis
servers.

I believe a lot of the code needs some
restructuring at some point down the line to
handle multiple connections in a cleaner way, but
for now it'll do.

spec/spec_helper.rb

@@ -9,4 +9,4 @@ require 'rspec/autorun'
 
 # use the test Redistat instance
 Redistat.connect(:port => 8379, :db => 15)
-Redistat.flush
+Redistat.redis.flushdb