simple client integration tests

Still need to add some sort of `@cassandra-version-specific @cassandra-version-2.0` to the C* 2.0 features. Also will need to update rake task in Rakefile/Travis to include the new integration tests suite.
take a look at https://github.com/datastax/ruby-driver/pull/6/files#diff-82df4ed556edb44e98c27db9156ef946R460 for an example of restricting tests to a certain cassandra version