Get tests passing in travis ci

Stuff you should know:
Each job should try to be under 30 minutes because travis times out jobs
at 40 minutes.

Each job has about 2 minutes and 45 seconds of overhead on travis which
is mostly taken up downloading stuff with maven and compiling code.  So
it is best not to go wild and split the jobs too small.

When travis jobs timeout they just report "error" and often don't log
why the error happened.

This configuration will take up about 2 and a half hours of build executor
time per push including pull requests.  That is about half an hour per
executor.  So, if you assume pushes com uniformly this means it'll support
about 48 a day.  If the queue is empty, it'll take about 40 minutes to get
a complete build.

How it works:
Split slow tests into batches so they take under 30 minutes each batch.

Disable openjdk6 because it isn't recommended for Elasticsearch and adding
a third executor will add 50% to the build time.