replace client with alia

This PR includes https://github.com/clojurewerkz/cassaforte/pull/5 (because of the collection type bug, for the tests to succeed). 

This replaces the internal client with alia, leaving the original api intact, 100% backward compatibility (with regards to the cql/query api). I took the liberty to make cql/execute private (not sure if that's ok with you, I dont know if you wanted to expose it at some point).

That was easier than I thought. Next we probably need to clean things up a bit and work on proper root aliasing.