Merge pull request #1252 from bradleypriest/renaming

Renaming a couple of hooks
Basic DS.ActiveModelSerializer implementation
custom JSON root
Get extraction working
rename rootForType hook to match
- Duplicate RESTSerializer serialize methods
- Basic polymorphic serialisation support
Add polymorphic hooks to JSONSerializer
Change polymorphic serialisation to a single hook
Use a less obtuse test object
update test
New naming conventions