Fix documented method name for DS.Transform#deserialize

Just a small typo.
Merge pull request #1599 from samsonjs/master

Fix documented method name for DS.Transform#deserialize
[BUG] Fix Serialization of Async belongsTo

Asynchronous belongsTo associations are Promises, and, as such, their
constructors were not being correctly identified. This change ensures
such relationships are always resolved before identifying their type.