Fixed example parameters

":prompt" parameter have to be second (if there are more than one use "{}")
Allow default selected tag
Update form_helper.rb
Update form_helper.rb
Update form_helper.rb
Merge pull request #30 from martinb35/master

":prompt" parameter have to be second (if there are more than one use "{}")
Allow users to pass an abbreviations option to subregion_select to display region abbreviations as the visible element in the option