Move models from Redis to ElasticSearch

[edsu]

Now that ElasticSearch is being used for storing tweets and Twitter users I think it makes sense to move our User, Trends, Places and Settings models from Redis to ElasticSearch. JSON stores more naturally in ElasticSearch without having to manually maintain id indexes. Redis will still be useful for caching and queuing work, so I think it makes sense to not remove Redis support completely.

[edsu]

All the models are stored in ElasticSearch now.