Define types for multiple and value

properties in Input.js.

`value` is used only in `static` type of Input and in that case
it is used only like <p> {value} </p>
Therefore it can be of any type.

src/Input.js

@@ -28,7 +28,9 @@ const Input = React.createClass({
     groupClassName: React.PropTypes.string,
     wrapperClassName: React.PropTypes.string,
     labelClassName: React.PropTypes.string,
-    disabled: React.PropTypes.bool
+    multiple: React.PropTypes.bool,
+    disabled: React.PropTypes.bool,
+    value: React.PropTypes.any
   },
 
   getInputDOMNode() {