Updated logger to return a unique log ID consisting of pid, epoch time, counter.

This ID can be captured and returned to user to aid debugging of reports.
(In other words, we should log errors and return the ID with a helpful
message rather than crashing with backtrace to users)

Logger now includes calling function's file, line no.
Remove caller from errorlog calls, this is now handled in errorlog itself
New script to "scrub" the envoy notice queue for a given notify cycle.

This is basically the same as the envoy cron job, except it skips mailing.
Merge pull request #166 from jbarrett/queue-scrubber

- New script to clear notification queues
- Logger additions