Remove zag-agent from www dependencies. Replace it with a numbat emitter.
Wrap the emitter in a facade that imitates the zag API so no metrics
calls need to change.

Remove the unused installation of bluebird.
Add new metrics config to the dev config.
Added a missing `new`.
Tweak the point generation a little bit.
Include the app environment in each timeseries point so we can dashboard
each deployment separately.
Even more metrics name cleanup, after looking at some example uses.
Removed the stray `metrics =`.