fix undefined functions

it renders!

common/app/App.jsx

@@ -1,7 +1,7 @@
 import React, { PropTypes } from 'react';
 
-import Nav from './components/Nav';
-import Footer from './components/Footer';
+import { Nav } from './components/Nav';
+import { Footer } from './components/Footer';
 
 export default class extends React.Component {
   constructor(props) {

common/app/components/Nav/Nav.jsx

@@ -46,7 +46,7 @@ export default class extends React.Component {
   render() {
     return (
       <Navbar
-        brand={ this._renderBrand() }
+        brand={ this.renderBrand() }
         className='nav-height'
         fixedTop={ true }
         toggleNavKey={ 0 }>
@@ -69,7 +69,7 @@ export default class extends React.Component {
             href='/bonfires'>
             Bonfires
           </NavItem>
-          { this._renderSignin() }
+          { this.renderSignin() }
         </Nav>
       </Navbar>
     );