Dialog Toastr

This patch would give the ability for a dialog box with similar appearance to the existing 'info toast' with the addition of an ok and cancel button where an ok callback can be defined.

<code>toastr.dialog("Would you like to make this your default?", "Default Location?", function() {
       // goDoSomethingFantasticOnOkClick();
});</code>

The styling is something rough to get it presentable but leaves something to be desired.
Does not break any existing dialog functionality, all tests passed.

Cheers, Jake.