Provide a REST endpoint interface to `register_start`

[ljgray]

Interactions with comet are currently only possible using either the kotekan dataset broker or the python API. This effectively prevents us from writing external systems (brokers, etc...) in anything other than python, and forces a comet dependency on python code for nothing more than a single function call at startup.

It would be nice to be able to register a startup time and config via a broker endpoint. This would likely require moving the registration logic out of Manager.regsiter_start into the broker, and reworking Manager.register_start to simply jsonify its input and send that to the broker.

This might require a bit of additional thought, since it does slightly break the responsibility scope of the broker and manager.

[ketiltrout]

This might require a bit of additional thought, since it does slightly break the responsibility scope of the broker and manager.

I'd argue this would be an improvement. It's better to have the broker do the work of determining what a "register-start" state looks like rather than the manager because other clients which interface directly with the broker without using the manager would need to re-implement that logic.

[ljgray]

I'm going to have a crack at this soon™ (I've been meaning to for a couple of weeks now...)