New version 28.20-1
    
    - Check the proxy attribute before accessing it (vponcova)
    - Check the noverifyssl attribute before accessing it (vponcova)
    - Don't access the url attribute (#1530428) (vponcova)
    - Use Fedora Server default partitioning in Atomic (jkonecny)
    - Clean code of Atomic install class (jkonecny)
    - Migrate Atomic install class (#1491287) (jkonecny)
    - Move Atomic install class to Anaconda (#1491287) (#1536853) (jkonecny)
    - Make sure that fetch_url is defined. (vponcova)