Add missing property `namespace` to `DS.RESTAdapter`

It is kindness that public API is clearly specified.
Merge pull request #774 from tricknotes/add-missing-property

Add missing property `namespace` to `DS.RESTAdapter`
`DS.Adapter.resolveMapConflict` can receive two arguments
Better YUIDocs
Merge pull request #890 from thomasboyt/docs

Better YUIDocs
Merge pull request #887 from tricknotes/remove-not-referenced-argument

`DS.Adapter.resolveMapConflict` can receive two arguments
Eliminate unused variables

I used jshint with '"unused": true' option.
Merge pull request #888 from tricknotes/eliminate-unused

Eliminate unused variables
ember now comes the from ember-source gem

Reduce some confusion
Merge pull request #892 from stefanpenner/remove_extra_ember

ember now comes the from ember-source gem