Tweak the form elements for the alert objects
Tweak the form elements for the alert objects

1. put an index on them (this will end up generating a hash instead of an array, but it'll mean the ids and names are actually unique).
2. pass in the topic, organisation, and document_type to the helpers that generate the options for the selects.
3. show any errors from the email signup or alerts

robinwhittleton/whitehall,alphagov/whitehall,askl56/whitehall,hotvulcan/whitehall,YOTOV-LIMITED/whitehall,alphagov/whitehall,ggoral/whitehall,YOTOV-LIMITED/whitehall,hotvulcan/whitehall,robinwhittleton/whitehall,hotvulcan/whitehall,askl56/whitehall,robinwhittleton/whitehall,YOTOV-LIMITED/whitehall,alphagov/whitehall,askl56/whitehall,askl56/whitehall,hotvulcan/whitehall,ggoral/whitehall,alphagov/whitehall,YOTOV-LIMITED/whitehall,ggoral/whitehall,ggoral/whitehall,robinwhittleton/whitehall