Rewrite of query system

[almasaeed2010]

This PR will address issues #241 and #238

[almasaeed2010]

We are facing one major issue now that we started indexing in a way that supports faceted-search. In the entities index, the content column must change from text to dynamic with properties. This is obviously a breaking change that requires us to release 3.0 and a migration step.

One solution is to add a new column to index data using the new data mapping type. This also requires users to rerun the indexing process but it won't stop the currently functional search. A big drawback to this is the size of the index. By indexing the same information twice, we would double the size of the index.

[almasaeed2010]

The simple query string needs to be changed to use an array of bool queries. The reason is that dealing with escaping is hard with faceted search. What we want to eventually get is similar to the following:

{
  "bool": {
    "must": [
      {
          "simple_query_string": {
             "fields": ["content.rdfs__type", "content.obi__organism"],
              "query": "term"
          }
      }
    ]
  }
}