Cmd._run(), as conceived for working with lib.App, is meant to be an
async method. To be conservative about changes, jw-pkg's legacy way
of handling _run() was kept when deriving from libApp, and async was
not propagated down to the _run() implementations. This commit
rectifies that before adding additional subcommands.
Signed-off-by: Jan Lindemann <jan@janware.com>