Migrate finagle-thrift/finagle-stream tests to ScalaTest

In preparation for 2.11.x finagle-thrift tests will migrate to ScalaTest


Remaining Work:
1) Finagle-Streams
2) 2.11.x testing
3) Conversation about FinagleClientThriftServerSpec structure
4) Renaming tests from *Spec -> *Test
5) Clean up commit history and conform to commit message standards
maybe make a context class?