Add support for hs2 api to use thrift over http

Hiveserver2 acts as service on the cluster for external applications. One way to implement access control to services on a hadoop cluster to have a gateway server authorizes service requests before forwarding them to the server. The knox project has taken this approach to simplify cluster security management.

Other services on hadoop cluster such as webhdfs and webhcat already use HTTP. Having hiveserver2 also support thrift over http transport will enable securing hiveserver2 as well using the same approach.