Update doc/MacRunOnBoot for OS X 10.9+ (It's 3 Years Old)

The MacRunOnBoot document is starting to get old:

• Vidalia is on the way out - should we include alternatives such as Terminal: "which tor" or arm?

• The launchd org.torproject.tor.plist can be significantly improved:

Log stdout and stderr

Wait for network before running tor

Play nice with other apps (CPU, I/O)

Open greater than the default 512/1024 file/connection limit

I'll attach an example, annotated torrc that I'm using on OS X 10.9.