Make it possible to view submission status on the speaker form

Previously, once the CfP was closed, the link would be gone until the talk
was either approved or rejected. Now it will go to a list where the talk
can no longer be edited, but it shows what the status is of the talk.
Add support for sending email to the speaker(s) of a specific session

This can be used to send approval and rejection notices. It's still
necessary to manually enter the contents of the email, but at least it
simplifies the tracking of some things.