Add proptype for className; update tests

Author: jwo

__tests__/__snapshots__/HoverImage.test.js.snap

@@ -22,6 +22,7 @@ ShallowWrapper {
     "key": null,
     "nodeType": "host",
     "props": Object {
+      "className": undefined,
       "onClick": [Function],
       "onMouseOut": [Function],
       "onMouseOver": [Function],
@@ -38,6 +39,7 @@ ShallowWrapper {
       "key": null,
       "nodeType": "host",
       "props": Object {
+        "className": undefined,
         "onClick": [Function],
         "onMouseOut": [Function],
         "onMouseOver": [Function],

build/index.js

@@ -516,7 +516,8 @@ var HoverImage = function (_React$Component) {
         style: this.props.style,
         onMouseOver: this.mouseOver,
         onMouseOut: this.mouseOut,
-        onClick: this.handleClick
+        onClick: this.handleClick,
+        className: this.props.className
       });
     }
   }]);

src/index.js

@@ -39,7 +39,8 @@ class HoverImage extends React.Component {
 }
 HoverImage.propTypes = {
   hoverSrc: PropTypes.string.isRequired,
-  src: PropTypes.string.isRequired
-}
+  src: PropTypes.string.isRequired,
+  className: PropTypes.string
+};
 
 export default HoverImage