Implement queryRecord

[bmac]

@thaume Any chance you have time to implement this one?

  /**
   `queryRecord` asks the adapter to fetch a single record using a query object.

   This method is asynchronous.

   @method queryRecord
   @param {String} type
   @param {Object} query
   @param {Object} options
   @return {DS.PromiseObject} record
   */
  queryRecord: function(type, query, options),

[HeroicEric]

If this is going to be added, would it be more consistent to have store.query be named store.queryAll?

[thaume]

@bmac I'm working on it over here https://github.com/emberjs/data/pull/2584/files

[bmac]

There was some talk about using queryAll for consistency with the findAll and peekAll however it was decided to stay with query because the records returned from the server by a query are likely a subset of all the record.

[bmac]

Closed by #2584