Upgrade to latest cql-rb

I've also:
 - bumped the default development ruby version
 - deleted Gemfile.lock (you don't really want to check that in for gems)
 - removed the separate development dependency on rake (apparently you don't need that anymore if it's also a runtime dependency

All the specs pass.

The version of cql-rb I'm using is still -pre, so we might not want to push this to rubygems until that's actually released. Depends on how you feel about pre-release dependencies.