Fix propType tests for latest React (v15.2.0) (#176)

* Add missing comma in readme

* ✅ Fix propType tests latest React

React 15.2.0 changed propType validation warning text:
https://github.com/facebook/react/blob/master/CHANGELOG.md#1520-july-1-2
016

Author: acusti

specs/draggable.spec.jsx

@@ -122,23 +122,35 @@ describe('react-draggable', function () {
 
       TestUtils.renderIntoDocument(drag);
 
-      expect(console.error).toHaveBeenCalledWith('Warning: Failed propType: Invalid prop className passed to Draggable - do not set this, set it on the child.');
+      expect(
+        console.error.calls.argsFor(0)[0].replace('propType:', 'prop type:').split('\n')[0]
+      ).toBe(
+        'Warning: Failed prop type: Invalid prop className passed to Draggable - do not set this, set it on the child.'
+      );
     });
 
     it('should throw when setting style', function () {
       drag = (<Draggable style={{color: 'red'}}><span /></Draggable>);
 
       TestUtils.renderIntoDocument(drag);
 
-      expect(console.error).toHaveBeenCalledWith('Warning: Failed propType: Invalid prop style passed to Draggable - do not set this, set it on the child.');
+      expect(
+        console.error.calls.argsFor(0)[0].replace('propType:', 'prop type:').split('\n')[0]
+      ).toBe(
+        'Warning: Failed prop type: Invalid prop style passed to Draggable - do not set this, set it on the child.'
+      );
     });
 
     it('should throw when setting transform', function () {
       drag = (<Draggable transform="translate(100, 100)"><span /></Draggable>);
 
       TestUtils.renderIntoDocument(drag);
 
-      expect(console.error).toHaveBeenCalledWith('Warning: Failed propType: Invalid prop transform passed to Draggable - do not set this, set it on the child.');
+      expect(
+        console.error.calls.argsFor(0)[0].replace('propType:', 'prop type:').split('\n')[0]
+      ).toBe(
+        'Warning: Failed prop type: Invalid prop transform passed to Draggable - do not set this, set it on the child.'
+      );
     });
 
     it('should call onStart when dragging begins', function () {