[thrift] Ruby TThreadedServer and TThreadPoolServer

[thrift] Ruby TThreadedServer and TThreadPoolServer

Summary: They both use the same handler for all connections and thus assume the handler is thread-safe. The TThreadPoolServer preserves threads, so it wouldn't be too hard to make a variant that used a separate handler for each thread and thus didn't require thread safety.

Reviewed By: mcslee

Test Plan: loads without error

Revert Plan: ok

Other Notes: contributed by William Morgan (w@adap.tv)

git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@665438 13f79535-47bb-0310-9956-ffa450edef68