hydrateInstance
Returns an instance given raw data, returning it from the instanceStore if available.
    connection.hydrateInstance(props)
  
  Overwrites the base hydrateInstance so that if a matching instance is in the
instanceStore, that instance will be
updated with props and returned.  If there isn't a
matching instance, the base hydrateInstance will be called.
Parameters
- props 
{Object}:the raw data used to create an instance