Better error handling and recovery

We've added better error handling and recovery when looking for gmail messages with large attachments. Scanning your large mailbox can take anything from 10 to 60 minutes. It varies a lot by location (our servers are in California USA) and time of day (mornings are slower). There may also be errors when we request sizes, and sometimes the queries aren't answered at all. Based on our recent experiences we rolled out some major improvements in how we handle this. So far there have been no failed scans since we did this! Keep those searches coming!