Addition of fsevents notification system

[xor-gate]

Now only inotify on linux works, possible people don't have yet tested on Mac OS X but a feature using fsevents would be nice.

As reference this project could be used which implements both inotify and fsevents:
https://github.com/axkibe/lsyncd

[brettsheffield]

Thanks. There is a new version of should in the pipeline, and fsevents is on the TODO list, but not yet implemented. We did look at lsyncd in 2008, but not recently. Back then it had an rsync call in the middle of it's event loop which meant it missed more events than it caught. No use for watching Maildirs, which trigger lots of events.