Description of problem:
libguestfs (and virt-customize) allows to install packages in the VM using the "install" keyword. It also allows to upgrade the system using the "update" keyword. But sometimes it would be useful to uninstall a package from the existing image, thus I propose to add an "uninstall" option, which basically reverses the "install" one.

Version-Release number of selected component (if applicable):
libguestfs-1.33.34-1.fc24.x86_64, but also others.