Update README.md

[laverboy]

Add information about how to get the form and html extensions to work. It just took me two hours to get it working, so it may help someone else.

[coveralls]

Coverage remained the same at 24.61% when pulling 9704f87 on laverboy:patch-1 into 0e2693d on rcrowe:master.

[barryvdh]

Perhaps just add that line:

In order to use the included Form and Html extensions you will need install the Laravel Collective Html package. Remember to add 'Collective\Html\HtmlServiceProvider' to your config/app.php file.
(Remembering->Remember)