Improve testing harness to allow tests on real devices (#197)

* test_cli: provide return values to patched objects to avoid warning about non-awaited calls

* test_cli: restore alias after testing

* smartstrip: remove internal update() calls for turn_{on,off}, set_led

* Make sure power is always a float

* Fix discovery tests

* Make tests runnable on real devices

* Add a note about running tests on a real device

* test_strip: run update against the parent device

kasa/cli.py

@@ -247,6 +247,7 @@ async def alias(dev, new_alias, index):
     if new_alias is not None:
         click.echo(f"Setting alias to {new_alias}")
         click.echo(await dev.set_alias(new_alias))
+        await dev.update()
 
     click.echo(f"Alias: {dev.alias}")
     if dev.is_strip: