REST API refactor: return added object only on create/delete

Respond only with the added resource JSON, not the full list of
objects.  The earlier method was due to shortcomings in the UI ajax
code, the new approach is how most REST APIs work (incl. AngularJS).
Use 'use strict'
Use LIMIT 1 for single row queries
Hlint fixes

Whoah, would you do changes like this in a non-statically typed
language? :P