Don't break when system timezone is UTC

.travis.yml

@@ -1,4 +1,6 @@
+sudo: false
 language: python
+cache: pip
 python:
   - "2.7"
   - "3.3"

jrnl/DayOneJournal.py

@@ -51,7 +51,13 @@ class DayOne(Journal.Journal):
                     except (KeyError, pytz.exceptions.UnknownTimeZoneError):
                         timezone = tzlocal.get_localzone()
                     date = dict_entry['Creation Date']
-                    date = date + timezone.utcoffset(date, is_dst=False)
+                    try:
+                        date = date + timezone.utcoffset(date, is_dst=False)
+                    except TypeError:
+                        # if the system timezone is set to UTC,
+                        # pytz.timezone.utcoffset() breaks when given the
+                        # arg `is_dst`
+                        pass
                     entry = Entry.Entry(self, date, text=dict_entry['Entry Text'], starred=dict_entry["Starred"])
                     entry.uuid = dict_entry["UUID"]
                     entry._tags = [self.config['tagsymbols'][0] + tag.lower() for tag in dict_entry.get("Tags", [])]