Bug 1075138 — Add the reason when Hello call state is terminate.

https://bugzilla.mozilla.org/show_bug.cgi?id=1075138
hmm, this is pretty much tied to how we're currently storing the data in the database (and will change I believe in the future with MySQL).

Instead of that, we could consider adding the information to the database directly when we set the state, and do not use the counting mechanism to know what's the state of the call.