added addhttp
added addhttp

This function ensures passed $url starts with http or https depending on the scheme.

Usage:

````
$url = 'novaframework.com';
$url = add_http($url); //http://novaframework.com
````
LuckyCyborg/simple-mvc-framework,LuckyCyborg/simple-mvc-framework,geomorillo/framework,XTRO123/framework,simple-mvc-framework/framework,nova-framework/framework,simple-mvc-framework/framework,geomorillo/framework,LuckyCyborg/simple-mvc-framework,nova-framework/framework,XTRO123/framework,LuckyCyborg/simple-mvc-framework,LuckyCyborg/framework,LuckyCyborg/framework,geomorillo/framework,XTRO123/framework