bin/fswatch.sh: Fix while loop && add script output

This uses a proper while loop implementation and outputs the file
copy results upon a fswatch event. The use of a proper while loop
drops CPU usage of fswatch from ~99% to ~0%.
bin/fswatch.sh: Add debug logging && launchd

* Introduce bin/org.ttcards.fswatch.plist; this is the launchd (OSX)
script I use for automatically launching fswatch at user login. This
file serves as an example for others. Documentation for how to use
this launch script has been added to bin/fswatch.sh.