keep compatibility with indicators

This project is yours, but it's archived, i can't make a direct PR. You could give it a second chance, because some developers like eth-p have maintained it up-to-date, I've fixed more issues, it's working.
It's useful for some users to keep compatibility with other applications available in AppCenter like Ubuntu apps or flatpack (Skype, Riot). I think it would be great to allow people keeping the ubuntu indicators, if they want to.