Use better import syntax of ts + react

src/DatePicker.tsx

@@ -1,4 +1,4 @@
-import React from 'react';
+import * as React from 'react';
 import MultiPicker from 'rmc-picker/lib/MultiPicker';
 import Picker from 'rmc-picker/lib/Picker';
 import IDatePickerProps from './IDatePickerProps';

src/Popup.tsx

@@ -1,4 +1,4 @@
-import React from 'react';
+import * as React from 'react';
 import IDatePickerProps from './IDatePickerProps';
 import PopupPicker from 'rmc-picker/lib/Popup';
 import { IPopupPickerProps } from 'rmc-picker/lib/PopupPickerTypes';

tests/DatePicker.spec.js

@@ -1,4 +1,4 @@
-import React from 'react';
+import * as React from 'react';
 import { render/*, mount*/ } from 'enzyme';
 import { renderToJson } from 'enzyme-to-json';
 import DatePicker from '../src';