install and use prop-types over React.PropTypes

Signed-off-by: Michael Telatynski <7t3chguy@gmail.com>

src/components/views/context_menus/GenericTextContextMenu.js

@@ -16,7 +16,8 @@ limitations under the License.
 
 'use strict';
 
-import React, {PropTypes} from 'react';
+import React from 'react';
+import PropTypes from 'prop-types';
 
 export default class GenericTextContextMenu extends React.Component {
     static PropTypes = {