Migrate to Elasticsearch 1.x

This migrates Archivematica to Elasticsearch 1.x (tested with 1.3.4), and the official Elasticsearch Python library instead of pyes.

Known issues:

* [x] Number of files in an AIP does not display correctly in the advanced search view
Right now I'm just trying to match the original internal API, so I'm avoiding renaming functions where necessary. Can look at a bigger refactor once we figure out what we're doing with search. :b

Meanwhile, reproduced the original behaviour, so I removed the comment.