fix(defaultValue): fix nested keys to work with default values

defaultValue now uses $parse to set keys

refs #468

Author: dfromero

src/directives/formly-field.js

@@ -110,7 +110,8 @@ function formlyField($http, $q, $compile, $templateCache, $interpolate, formlyCo
 
     function setDefaultValue() {
       if (angular.isDefined($scope.options.defaultValue) && !angular.isDefined($scope.model[$scope.options.key])) {
-        $scope.model[$scope.options.key] = $scope.options.defaultValue;
+        const setter = $parse($scope.options.key).assign;
+        setter($scope.model, $scope.options.defaultValue);
       }
     }
 

src/directives/formly-field.test.js

@@ -511,7 +511,7 @@ describe('formly-field', function() {
         scope.fields.push(secondField);
       });
 
-      it.skip(`should set the default value for nested keys`, () => {
+      it(`should set the default value for nested keys`, () => {
         compileAndDigest();
         expect(scope.model.foo.bar).to.equal(defaultValue);
         expect(scope.model.baz[0]).to.equal(defaultValue);