Scc 5168

[danamansana]

Initial work for NYQL. Still a work in progress, but so far we have:

• A mapping defining the fields used for different types of search scopes. Where applicable, I've based this on the existing search scopes, or filters
• A grammar for parsing CQL queries
• Methods to transform CQL queries into ElasticSearch
  EDIT: Merged in some other tickets which add:
• date-related queries
• compatibility with filters
• and related tests
• some error handling/error messages
• a compact representation of the parsed query, returned in the API response

(this covers SCC-5168/69/70)

Still to come:

• the == operator
• handling ES responses, particularly for inner_hits
• need some more attention to issues around escaping
• syntactic sugar in the grammar to make it more permissive