Stats Publish

[GDYendell]

These are two somewhat isolated changes to allow odin to complete a control loop between a motion controller moving some attenuators and the exposure on a detector. These are:

• Extend SumPlugin to calculate a histogram as well as total counts
• Create ParameterPublishPlugin to publish any parameters on a frame as json over ZeroMQ

I imagine these two features could be useful for other things.

• [x] Waiting on #301

[GDYendell]

This is ready for review when you get a chance.

I think it is pretty noninvasive. The behavior SumPlugin is intended be the same as before unless histogram bin thresholds are configured (excluding some additional checks and iterating of empty containers).

[GDYendell]

Deferring for now. Need to figure out whether to split this into its own plugin or have it only at DLS.