Email notification - text is awkward if we have no address for the unit

[franck-boullier]

The problem:

When we have no address information for a unit, the text of the notification is awkward as it assumes that the address will always be there

Current text if there is no address is

(...) Case 3 - Unit 1 - 11June19 has been reported in Unit 1 - 11Jun19 at and (...)

Suggested solution:

If we have no address information for the unit, then remove the unnecessary at and change the text to

(...) Case 3 - Unit 1 - 11June19 has been reported in Unit 1 - 11Jun19 and (...)