fix(ngModelAttrsManipulator): Override existing attributes

If you're explicitly specifying  then it's likely you'll want to override exisitng
attributes in the template. This should have been the default.

BREAKING CHANGE: If you were depending on the behavior before of not overriding existing properties,
this will break you.

Author: Kent C. Dodds

src/run/formlyNgModelAttrsManipulator.js

@@ -127,7 +127,7 @@ function addFormlyNgModelAttrsManipulator(formlyConfig, $interpolate, formlyWarn
 
     function addNgModelElAttrs() {
       angular.forEach(options.ngModelElAttrs, (val, name) => {
-        addIfNotPresent(modelNodes, name, val);
+        addRegardlessOfPresence(modelNodes, name, val);
       });
     }
   }

src/run/formlyNgModelAttrsManipulator.test.js

@@ -362,6 +362,14 @@ describe('formlyNgModelAttrsManipulator', () => {
       ).to.equal('{{::to.bar}}');
 
     });
+
+    it(`should override existing attributes`, () => {
+      field.ngModelElAttrs = {
+        'ng-model': 'formState.foo.bar'
+      };
+      manipulate();
+      expect(resultEl.attr('ng-model')).to.equal('formState.foo.bar');
+    });
   });