Linux fixes

[berarma]

I'm again at it with some more install script polishes. Sorry for the rushed first PR, I hoped to get some more time for refinement before you merged but it didn't happen. :smile:

I've also made some minor fixes:

• When launching the app on Gnome it would show "run.py" instead of the app name in some places: desktop notifications, alt-tab switcher and the overview dash bar.
• It was possible to launch several instances of the app instead of switching to the already open one. It's still possible to open more than one instance from the command line but I don't think it matters.

Thanks!

[s-victor]

Awesome! There is no rush, thank you very much for the help.