Avoid problems with wrong timestamps (bug 352)

I've search a little and it seems that it comes
from podcasts that are on my iPod and that don't
have a released date.

I've just attached my version of util.py. I've
added a try/except, so if the timestamp is not None,
but is incorrect, the exception is catched and None
is returned. It works for me.

src/gpodder/gui.py

@@ -105,7 +105,7 @@ app_authors = [
     'Ortwin Forster', 'Paul Elliot', 'Paul Rudkin',
     'Pavel Mlčoch', 'Peter Hoffmann', 'PhilF', 'Philippe Gouaillier', 'Pieter de Decker',
     'Preben Randhol', 'Rafael Proença', 'R.Bell', 'red26wings', 'Richard Voigt',
-    'Robert Young', 'Roel Groeneveld',
+    'Robert Young', 'Roel Groeneveld', 'Romain Janvier',
     'Scott Wegner', 'Sebastian Krause', 'Seth Remington', 'Shane Donohoe', 'Silvio Sisto', 'SPGoetze',
     'S. Rust',
     'Stefan Lohmaier', 'Stephan Buys', 'Steve McCarthy', 'Stylianos Papanastasiou', 'Teo Ramirez',

src/gpodder/util.py

@@ -301,7 +301,11 @@ def format_date(timestamp):
 
     today = time.localtime()[:3]
     yesterday = time.localtime(time.time() - seconds_in_a_day)[:3]
-    timestamp_date = time.localtime(timestamp)[:3]
+    try:
+        timestamp_date = time.localtime(timestamp)[:3]
+    except ValueError, ve:
+        log('Warning: Cannot convert timestamp', sender=self, traceback=True)
+        return None
     
     if timestamp_date == today:
        return _('Today')