Fix for Issue #178
If an action is selected and no objects are selected the message "Items must be selected in order to perform actions on them. No items have been changed." is displayed instead of the user being sent to Action confirmation screen.
Merge branch 'drop_down_fires_nothing_selected' of git://github.com/waustin/django-admin2 into waustin-drop_down_fires_nothing_selected
Test fixes