CPP-149 Token Aware Routing

Token Aware routing rebased following schema meta rewrite.

I have done minimal, spot-check testing with Murmur3 and Random partitioners. Posting this to get review feedback as I continue a few more basic tests.
Oversight.
https://github.com/datastax/cpp-driver/commit/b4eede4d39333aafe6ad2bfb07333c2b25b32f42