Allow wizard to skip disabled steps

Hi Vince, 

By using the master of your bootstrap wizard I was unable to allow the wizard to skip past disabled steps, so I wrote this patch :)

Hope you find it useful!

Cheers

Ps: the screen shot below shows what I mean - in this example, 'Fee details' will be skipped out.

![screen shot 2013-06-25 at 09 56 37](https://f.cloud.github.com/assets/1872162/701465/b2027ce2-dd75-11e2-9ed8-a5c5b0ed0e07.png)