Add dot-notated field support

[zarathustra323]

Allow for get() related methods on the Store to support dot-notated field keys. For example, on an event model with a review relationship, allow for get('review.name') to return the name value from related review model.

A hasMany relationship would be similar, but would return an array of values. For example, on an event model with a tags hasMany relationship, get('tags.name') would return ['name 1','name 2']

This should be recursive: get('review.person.name') would return the name of the person from the review off the event