Date formatting

Here's a fully locale-aware attempt at more readable dates. The Android DateFormat has the method getBestDateTimePattern(), which can automatically adapt format strings to the locale. I used this to create a short date format without the year for the drawer and entries lists. The short date looks as follows

Jan 6 (US English)
6 Jan (UK English)
6 jan (Swedish)
6. tammikuuta (Finnish (yes, we're weird))

I also changed the code to display only the time (same automatic formatting as before) for updates/entries within the past 24 hours. After that, both the short date and the time is shown. EntryView shows getLongDateFormat(), with the full name of the month.