Autotest: Design and implement RPM Server Infrastructure.

Created the RPM Frontend and Dispatch Servers. The Frontend is
responsible for accepting RPM requests from clients and fielding them
out to dispatchers. The dispatchers are responsible for managing
RPMController instances which will communicate with the RPM devices.

MultiThreadedXMLRPCServer is a simple class that allows us to have
multithreaded xmlrpcserver instances and accept multiple requests.

BUG=chromium-os:30955
TEST=Simple Integration Test in 'test_client.py'. Along with simple
unittests for frontend_server.

Change-Id: I337a019b4496b0fa4e01dbb1625c19b1b45693fd
Reviewed-on: https://gerrit.chromium.org/gerrit/27084
Reviewed-by: Scott Zawalski <scottz@chromium.org>
Commit-Ready: Simran Basi <sbasi@google.com>
Tested-by: Simran Basi <sbasi@google.com>
11 files changed