Sending mails to instructors on any changes/updates in ALT

[jalote]

We have email addrs of any instructor who uses ALT. It will be good to have a function which can identify all the currently active courses and get the email ids of the instructors of these courses (as csv, say). Then for any intimation about any major changes / updates, an email can be sent to the instructors. (Perhaps sending the email can also be done through the function, but for now it can be sent manually also - as updates may not be very frequent.)

Optional: If we have emails of students also, any changes on the student interface - an email can be sent to them. If we dont have their emails, it is fine - any urgent/important change we can send to instructors (who can email it to students or post it as a message on ALT itself)