Recent time entries

Time.all was only returning time entries for a given day, so I renamed it to Time.by_date.  

Time.all (without arguments) behaves exactly as it used to (I didn't break the API).  But *with* arguments, it now returns multiple days' time entries.

Also added Time.recent, which returns the most recent *limit* time entries -- by default, the most recent 10 entries over the past week.