Adds support for installing laravel 5

If you use the flag --dev it will install Laravel 5 instead of 4. 

I tried downloading it directly from github, but it said that it could not confirm the SSL certificate, even though I was using http:// ... :/ . So I used GH pages and it works fine. That said this may not always be perfectly up to date, but I will try to update it as soon as I see a change. That is unless Taylor puts it on laravel cabinet!