Update project to work with Django 1.10.x

manage.py

@@ -4,7 +4,20 @@ import sys
 
 if __name__ == "__main__":
     os.environ.setdefault("DJANGO_SETTINGS_MODULE", "mayan.settings")
-
-    from django.core.management import execute_from_command_line
-
+    try:
+        from django.core.management import execute_from_command_line
+    except ImportError:
+        # The above import may fail for some other reason. Ensure that the
+        # issue is really that Django is missing to avoid masking other
+        # exceptions on Python 2.
+        try:
+            import django
+        except ImportError:
+            raise ImportError(
+                "Couldn't import Django. Are you sure it's installed and "
+                "available on your PYTHONPATH environment variable? Did you "
+                "forget to activate a virtual environment?"
+            )
+        raise
     execute_from_command_line(sys.argv)
+