update imports for Django 1.8

Author: bwademackevision

simple_history/admin.py

@@ -7,7 +7,10 @@
 from django.contrib.contenttypes.models import ContentType
 from django.core.urlresolvers import reverse
 from django.shortcuts import get_object_or_404, render
-from django.contrib.admin.util import unquote
+try:
+    from django.contrib.admin.utils import unquote
+except ImportError:
+    from django.contrib.admin.util import unquote
 from django.utils.text import capfirst
 from django.utils.html import mark_safe
 from django.utils.translation import ugettext as _

simple_history/models.py

@@ -11,7 +11,11 @@
 from django.db.models.fields.related import RelatedField
 from django.conf import settings
 from django.contrib import admin
-from django.utils import importlib, six
+try:
+    import importlib
+except ImportError:
+    from django.utils import importlib
+from django.utils import six
 from django.utils.encoding import python_2_unicode_compatible
 from django.utils.encoding import smart_text
 from django.utils.timezone import now

simple_history/tests/tests/test_admin.py

@@ -8,7 +8,10 @@
     User = get_user_model()
 except ImportError:  # django 1.4 compatibility
     from django.contrib.auth.models import User
-from django.contrib.admin.util import quote
+try:
+    from django.contrib.admin.utils import quote
+except ImportError:  # django 1.7 compatibility
+    from django.contrib.admin.util import quote
 from django.conf import settings
 from simple_history.models import HistoricalRecords