Create controller.py
Fix stuff in controller.py
Add stubs: basic_source.py and basic_sink.py
Improve the basic_source and basic_sink examples
Add ROUTER socket to controller.py
Switch to using threads
Use Event instead of Lock to signal termination
Add stub RequestsThread class
Fill-in RequestsThread
Add stub for ServicesThread class
Extent RequestsThread and ServicesThread
Make basic request/reply work
Make split_request_message not return JSON
Reorder methods in thread classes
Fix basic_request example
Add controller configuration via a file

a configuration file other than the default (./controller.conf) can be
specified with the -c, --config parameter
Add rpisps module directory and files
rpispscontext.py: Import missing rpisps.constants
rpispscontext.py: Make request/write_value return reply
rpispscontext.py: Fix wrong typename in recv_updates