Another attempt at updating kumascript to new process model

Okay, so the last update showed processes randomly dying after deploy to prod. I haven't been able to reproduce this, neither on my dev laptop nor on an EC2 machine.

So, this update introduces two things:

* A bunch of revised statsd measurements to maybe help diagnose failures
* Code to retry failed macros several times, since the process failures appeared to be transient. (eg. The same macro, run 100 times on a page failed 2-5 times in different spots with different reloads)

Hopefully this can make these changes deployable so I can try to diagnose why some processes fail.