21224 rest api queries

re-usable library + restrouter implementation

https://github.com/tjwebb/xtuple/blob/21224-rest-api-queries/node-datasource/lib/query/README.md

Unit tests are pure mocha and not hooked into test-runner right now. But they are all pass and can be run like so: `mocha -R spec test/routes/query.js`