Updated to boost relevance in a Elasticsearch >= 1.0 way

Note: Don't merge this until the backend Elasticsearch has been upgraded to 1.0 or later.

Note: This will require a completely new index after upgrading to Elasticsearch 1.0 because it requires a new mapping to be put in place.

After ES upgrade you can create a new index and point the old alias to it but we should build a command to re-index all the projects. I could work on that here and there but I'll file an issue for it.