Add Scope#scope method

The `Model` class has a `scope()` method to return the scope for it.
It would be nice to be able to pass in either a model or a scope to the
a function and use the `scope()` method to cast it to a scope
regardless, instead of doing type detection.

Author: wadetandy

src/scope.ts

@@ -95,6 +95,10 @@ export default class Scope {
     return this;
   }
 
+  scope() : Scope {
+    return this;
+  }
+
   asQueryParams() : Object {
     let qp = {};
 

test/unit/scope-test.ts

@@ -118,6 +118,12 @@ describe('Scope', function() {
     });
   });
 
+  describe('#scope()', function() {
+    it('returns itself', function() {
+      expect(scope.scope()).to.equal(scope)
+    })
+  })
+
   describe('#asQueryParams()', function() {
     it('transforms all scoping criteria into a jsonapi-compatible query param object', function() {
       scope