Configure words to ignore in full text search

+ Add script to rename CIP keywords from JSON that has the mapping of CIP keyword to OpenEligibility taxonomy
Add support for nested categories via mongoid_nested_set

https://github.com/55ideas/mongoid_nested_set
Add rake task to create OpenEligibility categories
Configure mongoid_search to match all search terms

Using :any gave too many results, many of which weren't necessarily relevant.

Also set minimum word size to 4, so that it doesn't index words like "a", "and", "to", "of", etc..
Refactor API to use Grape & remodel DB structure

Lots of changes:

- Grape instead of RocketPants for API design
- Documentation via Swagger instead of Apiary. Docs are auto-generated from the API code in app/api/ohana.rb
- ROAR for representations
- Elasticsearch instead of mongoid_search
- Organize tests into components