Issue 4044: Search overhaul, part 1

Issue 4044: Search overhaul, part 1

This is just the json generation and indexing bits to send data to the new Elasticsearch cluster, with rake tasks to do a full reindex. We still need to hook it into the callbacks -> redis buffer cycle and create the new search classes. 

https://code.google.com/p/otwarchive/issues/detail?id=4044
If the index's existence is a requirement, should there be a guard against trying to run this code without an index (i.e. check if it exists and create it if not, for example, or raise an exception?)