Added default to <CheckboxInput/> value to fix warning in console.

src/components/inputs/CheckboxInput.jsx

@@ -3,11 +3,15 @@ import PropTypes from 'prop-types'
 
 class CheckboxInput extends React.Component {
   static propTypes = {
-    value: PropTypes.bool.isRequired,
+    value: PropTypes.bool,
     style: PropTypes.object,
     onChange: PropTypes.func,
   }
 
+  static defaultProps = {
+    value: false,
+  }
+
   render() {
     return <label className="maputnik-checkbox-wrapper">
       <input