[controller] Extracting startup welcome text into its own method
[controller] moving welcome text call into main program

Printing welcome text in the constructor of the controller was somehow messy
(don't ask me why, I don't really know why myself, but it feels like the
role of the controller's init *isn't* to print a welcome message).
[controller] defining encrypted file path in constructor

This isn't really the right place for it either, but this allows us to more
easily change the name of the encrypted file such that read_db_file() can be
tested automatically.  At some stage we want to push information such as
this out into a configuration object of some kind.
[tests/controller] adding skipped test for reading nonexistent db file