Fix create system class with relation/pointer

spec/Schema.spec.js

@@ -422,6 +422,43 @@ describe('Schema', () => {
     });
   });
 
+  it('creates non-custom classes which include relation field', done => {
+    config.database.loadSchema()
+    .then(schema => schema.addClassIfNotExists('_Role', {}))
+    .then(mongoObj => {
+      expect(mongoObj).toEqual({
+        _id: '_Role',
+        createdAt: 'string',
+        updatedAt: 'string',
+        objectId: 'string',
+        name: 'string',
+        users: 'relation<_User>',
+        roles: 'relation<_Role>',
+      });
+      done();
+    });
+  });
+
+  it('creates non-custom classes which include pointer field', done => {
+    config.database.loadSchema()
+    .then(schema => schema.addClassIfNotExists('_Session', {}))
+    .then(mongoObj => {
+      expect(mongoObj).toEqual({
+        _id: '_Session',
+        createdAt: 'string',
+        updatedAt: 'string',
+        objectId: 'string',
+        restricted: 'boolean',
+        user: '*_User',
+        installationId: 'string',
+        sessionToken: 'string',
+        expiresAt: 'date',
+        createdWith: 'object'
+      });
+      done();
+    });
+  });
+
   it('refuses to create two geopoints', done => {
     config.database.loadSchema()
     .then(schema => schema.addClassIfNotExists('NewClass', {

src/Schema.js

@@ -48,13 +48,13 @@ var defaultColumns = {
   // The additional default columns for the _User collection (in addition to DefaultCols)
   _Role: {
     "name":  {type:'String'},
-    "users": {type:'Relation',className:'_User'},
-    "roles": {type:'Relation',className:'_Role'}
+    "users": {type:'Relation', targetClass:'_User'},
+    "roles": {type:'Relation', targetClass:'_Role'}
   },
   // The additional default columns for the _User collection (in addition to DefaultCols)
   _Session: {
     "restricted":     {type:'Boolean'},
-    "user":           {type:'Pointer', className:'_User'},
+    "user":           {type:'Pointer', targetClass:'_User'},
     "installationId": {type:'String'},
     "sessionToken":   {type:'String'},
     "expiresAt":      {type:'Date'},