Bug 828446 - [email/IMAP] timezone offset calculation breaks if timezone offset < -7 or > 7. will result in duplicate messages.

r? @mozsquib

There were a few other cases where we didn't have an explicit radix:
- the last bit of SUID's.  This is a straight-up base 10 value without padding, and there are a fair number of them.  As such, I just left them as-is (because they're not going to get an octal in there.)
- ActiveSync had two parseInts; I did modify these since I think they are always supposed to be decimal and it seems safer to hardcode us to base-10.