Support full-text search in metadata.search

[micahjsmith]

The FF metadata web app supports full-text real-time search using jQuery DataTables. It first downloads the 18mb file containing the entirety of the metadata and then filters it in the browser, rather than exposing any full-text search API.

Ideas to support full-text search in metadata.search:

1. download and cache the entire metadata json (http://metadata.fragilefamilies.princeton.edu/api/variable?details=1&q={%22filters%22:[]}) and filter it locally
2. construct a query over all of the text fields locally and issue that query against the metadata server

Note also that this json file is available which shows the full set of available filters:

curl -H 'Accept: application/json' http://metadata.fragilefamilies.princeton.edu/advanced_search