This lets some golint errors in, but fails if you're over a certain
threshold. The current threshold of 15% (of LOC) is arbitrary and
subject to change. The algorithm should be extended to check a range of
commits, although it's unclear how to detect what range of commits make
up a patch set.
We need to use sudo: required, and dist: trusty to avoid old versions of
bash in travis which don't support the -n argument to the `wait` shell
built-in.
We had to disable the -e checks in etcd.sh since the killall || killall
parts were causing those to trigger in travis.
