All reservations being added to notes e-mail

[orenyk]

From BMEC:

Also, I was wondering if there is a way that the email we receive with reservation notes could be restricted only to reservations that actually have notes typed in them. Right now, it appears we are getting a Notes email which includes every reservation whether or not someone has included a note.

It looks like since our make_notes method adds a header, the comparison we use to toggle the notes_unsent parameter is always returning true (since there are always new notes). I'm not sure this is worth patching in v3.4, I'll follow up with them and see. Either way, we should make sure that this implementation in master works as expected (#836, tests would be nice too :-D).