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 you try, Elasticsearch just tells you that you can't do it. It's one of their less oblique error messages, so I'm not sure it's worth catching it and raising a new one.