Add "Reviewed by Hound" badge

[salbertson]

I noticed there are two status updates being made for Hound. The capitalized version is the correct one, and you should be able to go into branch settings and uncheck hound to avoid the duplicate updates.

Here's a preview of the badge:

[CLAassistant]

All committers have signed the CLA.

[codecov-io]

Codecov Report

Merging #1273 into master will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master    #1273   +/-   ##
=======================================
  Coverage   34.25%   34.25%           
=======================================
  Files          36       36           
  Lines        2362     2362           
=======================================
  Hits          809      809           
  Misses       1450     1450           
  Partials      103      103

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[salbertson]

@akutz there are two status updates being made for Hound. The capitalized version is the correct one, and you should be able to go into branch settings and uncheck hound to avoid the duplicate updates.