More tests for bug fix #11009.

Abstract out making a session in WebGUI::Test.  Update POD
in Shop/Address.  Add tests for newBySession, showing that
the previous commit that allows update to update addressBookId
actually fixed the bug in question.

lib/WebGUI/Shop/AddressBook.pm

@@ -85,7 +85,9 @@ Deletes this address book and all addresses contained in it.
 
 sub delete {
     my ($self) = @_;
+    my $myId   = id $self;
     foreach my $address (@{$self->getAddresses}) {
+        delete $addressCache{$myId}{$address->getId};
         $address->delete;
     } 
     $self->session->db->write("delete from addressBook where addressBookId=?",[$self->getId]);