Added ability to configure number of shards and replicas

A modification that allows a user to configure the number of shards and/or the number of replicas when the index is automatically created by the river plugin.

Also, since this is essentially time series data, an option was added that allows the user the option of having the river automatically create new indexes either daily, weekly, monthly, or yearly (or use a single index) and have an automatic alias combining all the indexes together as a single query point. (i.e. number of indices @ http://www.elasticsearch.org/tutorials/using-elasticsearch-for-logs/)