Squashed commit of the following:

commit bb5081a78b
Author: Xeniac <xeniac@posteo.at>
Date:   Thu Nov 23 22:02:40 2017 +0100

    Added a setting where the exported excel files should be stored.
    Added a option to send the exported excel as mail attachment.

commit 854fd38740
Author: Xeniac <xeniac@posteo.at>
Date:   Thu Nov 23 22:01:38 2017 +0100

    Fixed: enumerate the Seasonrankings starting with 1
    Fixed: Logging error when a value changed from/to None

commit 6de1ecb102
Author: Christian Berg <xeniac@posteo.at>
Date:   Thu Nov 23 14:15:36 2017 +0100

    add a latest method to query the latest x events

commit bf12060c3b
Author: Christian Berg <xeniac@posteo.at>
Date:   Thu Nov 23 14:15:12 2017 +0100

    add a latest method to query the latest x events

commit 5ad628f33a
Author: Christian Berg <xeniac@posteo.at>
Date:   Mon Nov 20 07:47:47 2017 +0100

    Changed PlayerDanScore to only list non-legacy hanchans

commit 36272c60d6
Author: Christian Berg <xeniac@posteo.at>
Date:   Mon Nov 20 07:42:44 2017 +0100

    fixed import of MIN_HANCHANS_FOR_LADDER that moved to settings

commit c428f6ed1f
Author: Christian Berg <xeniac@posteo.at>
Date:   Mon Nov 20 07:41:04 2017 +0100

    Updated docstrings for new since and until kwargs

commit 9276e97c36
Author: Christian Berg <xeniac@posteo.at>
Date:   Mon Nov 20 07:33:54 2017 +0100

    added a since parameter to the hanchan queries to return only hanchans since the give date and time

commit fd244f10e8
Author: Christian Berg <xeniac@posteo.at>
Date:   Sun Nov 19 16:55:10 2017 +0100

    new command: resetdanranking YYYY-MM-DD, sets every dan player to 1st dan with zero dan_points at the given date.

commit 0a45cf1fd8
Author: Christian Berg <xeniac@posteo.at>
Date:   Sun Nov 19 16:14:59 2017 +0100

    added new fields to KyuDanRanking that allow to pick up the calculation from the last state of the KyuDanRanking.
    last_hanchan_date: it contains the start of the latest hanchan content for this players ranking.
    wins_in_row: to save the currents wins in a row

    Added option to calcuclate rankings until a given datetime.

src/events/views.py

@@ -30,7 +30,6 @@ class DeleteEventPhoto(PermissionRequiredMixin, mixins.EventDetailMixin,
 class EventArchiveIndex(mixins.EventArchiveMixin, generic.ArchiveIndexView):
     """Index of the event archive, displays the upcoming events first."""
     allow_empty = True
-    ordering = ('-start', '-end')
 
 
 class EventArchiveMonth(mixins.EventArchiveMixin, generic.MonthArchiveView):
@@ -73,7 +72,7 @@ class EventForm(PermissionRequiredMixin, mixins.EventDetailMixin,
             if self.kwargs.get('pk') else models.Event()
 
 
-class EventGallery(mixins.EventDetailMixin, generic.ListView):
+class EventGallery(generic.ListView):
     """Display a overview of all event photo albums."""
     template_name = 'events/photo_gallery.html'
     queryset = models.Event.objects.filter(