Payload: define txID to None.
Payload: forgotten comment in spaceRequired()
remove: configureAddOnRepo from the Payload interface.

It is never called from the outside.
Tweaks in the Payload interface.

Methods that don't need self are static. updateBaseRepo actually has a wider
signature.
refactor: move YumPayload._setUpMedia() up to PackagePayload._setupMedia().

So DNFPayload can share this.
refactor: extract the device handling in YumPayload._configureBaseRepo up to PackagePayload.

Do this so it can be shared with DNFPayload.
refactor: tear down the install device in PackagePayload.reset().

This allows the DNF payload to share the teardown code.
DNFPayload: initial version.
Enable DNFPayload on specific triggers.

DNFPayload is only enabled if 'dnf' is in /proc/cmdline or if '--dnf' is
passed to the Anaconda main executable.

Once DNFPayload is instantiated based on installclasses this commit can be
reverted.
packaging: add dnf to the Anaconda's requires.
dnf_img_test
Revert "Convert makeupdates from getopt to argparse"

This reverts commit 34712c368f0c400f1b0f0a2972f5586f6184b796.