No source in es

DO NOT MERGE. I'm creating this for review purposes.

Changes to prevent us from storing source document or source fields in ElasticSearch
See also: https://issues.apache.org/jira/browse/USERGRID-255
I worry that this will cause an outage.  Since we don't have seek (Cassandra) vs search (Elasticsearch) in the v1 v2 bridge code sorted out, I'm concerned we'll get incorrect results.  What if we used Shawn's changes to add aliases and performed the following in our migration?


1. Update the default mapping to your mapping
1. Allocate a new index, and set the write alias to it
1. Ensure the read alias points to old and new index
1. Perform the current re-index operation, this will write all entities to the new index and create new mappings
1. Delete the old index after the re-index is complete.