Set deployment target to OS X 10.6
Rename "dateFormatter" to "timeFormatter"

It better reflects what it does.
Show full date if data was updated more than 2 days ago

Right now, the data file hasn't been updated since April (and I'm
doubtful it will be -- looks like I missed the boat on publishing
this program!); if it's been more than 2 days since an update, show
the date instead of the time.