Fix activity view bug where an activity type id in the url overrides the actual activ...

Fix activity view bug where an activity type id in the url overrides the actual activity type id

When we view an activity there is code in the template that renders differently depending on the
activity type id. However, if the activity ID (atype) is wrong in the url it gives the url precedence

This is a bit obscure - I hit it when I changed the activity type id in the database & the view
did not update