fix crash when folder watcher fails

[davidnewhall]

This fixes the bug provided in #248.

What happens: When the app starts it initializes an fsnotify structure, but if no folders are defined it does not use it. If this initialization fails, for any reason, the app now has an uninitialized data structure and later crashes when it tries to read it. The bug discovered shows a failure in this initialization due to too many open files. Never seen this, and this bug has never been brought up until now.

So, to fix it, I did two things.

1. We no longer initialize fsnotify if there are no folders defined. This will avoid the too many open files problem.
2. If the fsnotify initialization fails, we still create the data structure to avoid crashing the app.