[Bug 832037] Update elasticutils; get new requirements

This updates to the master tip of elasticutils which uses pyelasticasearch.
It ditches pyes.
It adds pyelasticsearch and its requirements.

It fails tests because the code changes haven't been made, yet.
[Bug 832037] Update for pyelasticsearch-based elasticutils

This updates the codebase to use the pyelasticsearch-based elasticutils
from master tip.

Generally the changes are pretty minor. Most of them are to handle
the pyelasticsearch exceptions rather than the pyes ones. A few are
because some of the API bits changed in elasticutils. Then there's
some very minor cleanup.
PEP-8 pass.