Modify thrift_client to take in a "connector" function as a parameter, enabling subst...

Modify thrift_client to take in a "connector" function as a parameter, enabling substitution of different protocol/transports

Summary:
  Left in a backwards-compatible start_link with (Host, Port, Service) args

Test plan:
  tutorial/alterl still works

Notes:
  We may want to go a little further and get rid of the binary_protocol specific stuff from socket_transport as well

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@666460 13f79535-47bb-0310-9956-ffa450edef68