Allow optional "component" argument to Switcher

- This is the React component that will wrap the currently rendered
  Switch (if defined). Otherwise the Switch is rendered by itself.

Author: jdlehman

dist/switcheroo.min.js

@@ -41,3 +41,7 @@ The `defaultHandler` is the handler that is used when there are no `Switch` elem
 ```js
 onChange(match, pathname) { ... }
 ```
+
+### wrapper
+
+If the `wrapper` prop is defined, the rendered `Switch` will be wrapped in the specified React component. Any additional props passed to the `Switcher` will also be properties of this component.

docs/components/Switcher.md

@@ -1,5 +1,4 @@
 import React, {Component} from 'react';
-import NullComponent from './NullComponent';
 
 export default class Switcher extends Component {
   constructor(props) {
@@ -11,10 +10,10 @@ export default class Switcher extends Component {
     this.handleRouteChange = this.handleRouteChange.bind(this);
     this.getSwitch = this.getSwitch.bind(this);
 
-    this.defaultComponent = React.createElement(this.props.defaultHandler || NullComponent, this.props.defaultHandlerProps);
+    this.defaultSwitch = this.props.defaultHandler ? React.createElement(this.props.defaultHandler, this.props.defaultHandlerProps) : null;
     // set initial state
     this.state = {
-      visibleComponent: null
+      visibleSwitch: null
     };
   }
 
@@ -71,12 +70,21 @@ export default class Switcher extends Component {
     }
 
     this.setState({
-      visibleComponent: switchElement
+      visibleSwitch: switchElement
     });
   }
 
   render() {
-    return this.state.visibleComponent || this.defaultComponent;
+    if(this.props.wrapper) {
+      return React.createElement(
+        this.props.wrapper,
+        this.props,
+        this.state.visibleSwitch || this.defaultSwitch
+      );
+    }
+    else {
+      return this.state.visibleSwitch || this.defaultSwitch;
+    }
   }
 }
 
@@ -90,7 +98,8 @@ Switcher.propTypes = {
   pushState: React.PropTypes.bool,
   defaultHandler: React.PropTypes.func,
   defaultHandlerProps: React.PropTypes.object,
-  onChange: React.PropTypes.func
+  onChange: React.PropTypes.func,
+  wrapper: React.PropTypes.any
 };
 
 Switcher.defaultProps = {

modules/components/NullComponent.js

@@ -1,8 +1,13 @@
-import React from 'react/addons';
+import React, {Component} from 'react/addons';
 import {assert} from 'chai';
 import sinon from 'sinon';
 import Switch from 'components/Switch';
-import NullComponent from 'components/NullComponent';
+
+class NullComponent extends Component {
+  render() {
+    return false;
+  }
+}
 
 describe('Switch', function() {