Reload rework

[lclarkmichalek]

Reworks most of the HAProxy reloading code to be a little more testable (and adds tests), while keeping the logic mostly identical. Also adds the features in #158.

The major affect of all this is that

• We no longer exit if there is a problem trying to reload the haproxy config
• We have better logging in the area
  • The names of the statsd metrics were changed (well, I added a 2 and changed 1)
• We have a nice reliable way to test and cleanup config reloads.

Checklist:

• [x] Test
• [x] Document
• [x] Test on staging cluster for a while

[j1n6]

Do you mind squash the commits to sensible group?

• [x] Update README.md
• [x] Update example/dev config

[lclarkmichalek]

Done

[j1n6]

looks good :+1: let's test on staging before release.

[lclarkmichalek]

Seems hunky dory on staging. Merging and deploying.