✈️ migrate to static properies of ES7

proptypes should not be  capital
Add unit-test to check if separator has default value

src/components/Download.js

@@ -1,11 +1,20 @@
 import React from 'react';
 import {buildURI} from '../core';
-import {defaultProps as CommonDefaultProps, PropTypes} from '../metaProps';
-
+import {
+   defaultProps as commonDefaultProps,
+   propTypes as commonPropTypes} from '../metaProps';
 const defaultProps = {
   target: '_blank'
 };
 class CSVDownload extends React.Component {
+
+  static defaultProps = Object.assign(
+    commonDefaultProps,
+    defaultProps
+  );
+
+  static propTypes = commonPropTypes;
+
   constructor(props) {
     super(props);
     this.state={};
@@ -31,10 +40,4 @@ class CSVDownload extends React.Component {
   }
 }
 
-CSVDownload.defaultProps = Object.assign(
-  CommonDefaultProps,
-  defaultProps
-);
-CSVDownload.PropTypes = PropTypes;
-
 export default CSVDownload;