Dialog: unable to set any options but "closeBtn"

1. **Description:** `dialog`'s `_setOption` override prevents any options but `closeBtn` from being set.
1. **Test page:** http://jsbin.com/onibuc/250/edit
1. **Steps to reproduce:** `dialog.dialog({key: 'value'}); console.log(dialog.dialog('option', 'key'))`
1. **Expected outcome:** `'value'`
1. **Actual outcome:** `null`
1. **jQuery Mobile version:** 1.3.0rc1