Add persistent error logging to the mailer app.

mayan/apps/mailer/admin.py

@@ -0,0 +1,14 @@
+from __future__ import unicode_literals
+
+from django.contrib import admin
+
+from .models import LogEntry
+
+
+class LogEntryAdmin(admin.ModelAdmin):
+    date_hierarchy = 'datetime'
+    list_display = ('datetime', 'message')
+    readonly_fields = ('datetime', 'message')
+
+
+admin.site.register(LogEntry, LogEntryAdmin)