Australian addresses; Unit Numbers may not work correctly

Where an Australian address has a Unit Number without a type, eg 1 vs Flat 1, the address should include a slash; but this was not being added, instead 2 spaces were added.

This means that moving between a full address, eg "1/23 Main Street", and a split address and back will change the address to "1 23 Main Street" and cause issues.

The address conversion now includes a slash if the Unit Number does not include a type, for example:

Unit=1, Number=23 gives "1/23"
Unit= Flat 1, Number 23 gives "Flat 1 23".