Add a Datadog perfmetric for "important" requests

[Tres Seaver]

Figure out how to measure performance for dynamic (non-resource) requests.

E.g., perhaps those which are "text/html", "application/json"?

[Tres Seaver (tseaver)]

Added the perfmetric logging for 'timeit' requests:

  https://github.com/karlproject/karl/commit/5a87f14c9abf0fa7a8d0301c3445be61da57e3b1

Added the statsd configuration to the deployment stuff to enable the statsd client *before* timeit runs:

  https://github.com/karlhosting/osideploy/commit/d3b3156386a8529874e3d202094a262e8420648b

[Tres Seaver (tseaver)]

The data from karlstaging10 *is* making it to datadog.