Icon font input proposal for WP-Bootstrap-Navwalker. 

First draft for the input field in the backend, minor change in the wp-bootstrap-navwalker file.
Uses an extra file to put in theme directory, add 'include_once( 'wp_bstrp_nav_menu.php' );' 
before wp-bootstrap-navwalker line 'functions.php'. 
An icon font field will appear in the Menu Item settings page. 
TODO input validation/sanitization, code enhancements (eventually merge this extra file?)  

screenshots:
![github 1 - menus cristovao verstraeten wordpress - wptrunk_dev_wordpress_wp-admin_nav-menus_php](https://cloud.githubusercontent.com/assets/5374958/2600664/e0a9b8ec-bb02-11e3-9b04-fe3fb5912226.png)
![github 2 - menus cristovao verstraeten wordpress - wptrunk_dev_wordpress_wp-admin_nav-menus_php](https://cloud.githubusercontent.com/assets/5374958/2600666/f11dad82-bb02-11e3-80aa-8a6b519aaa12.png)
![github 3 - cristovao verstraeten i tailored wordpress development services - wptrunk_dev](https://cloud.githubusercontent.com/assets/5374958/2600678/2261241e-bb03-11e3-9a20-c306941b9e25.png)