Tagging Futile's camera as "MainCamera"

Apparently some 3rd party addins/plugins require the main camera to be
tagged as "MainCamera", so I did.

http://www.reddit.com/r/futile/comments/16gnjp/tagging_the_maincamera/
Fixing the FWatcher dummy implementation

FWatcher only really exists "for real" when being run in the editor, but
I accidentally missed writing a shell implementation of one of its
methods.