Notice: Undefined index: #title in mobile_jquery_radios()

Whether or not it's standard practice to require the #title attribute in form elements, it's not included a lot of the time. When using radio elements that have empty titles with the Mobile jQuery Theme, this patch prevents the error:

Notice: Undefined index: #title in mobile_jquery_radios() (line 125 of /mobile_jquery/includes/modules/form.inc).