In addition to monitoring the logs for errors, call a function (or
functions) that tell it to cancel the anaconda process and cleanup.
Also check for a cancel after creating the squashfs image for live-iso
since that's a long running process.
This required adding a new argument to a number of existing functions,
passing it down to QEMUInstall and novirt_install where the function is
called.
Resolves: rhbz#1656691
This moves everything except the cmdline checking into run_creator in
pylorax.creator
It also rearranges some functions to prevent import loops, and adds a
utility function to imgutils (mkfsimage_from_disk for copying a
partition into a filesystem image).
This reduces the amount of code in livemedia-creator to the cmdline
parsing and calling of the installer functions. Moving them into other
modules will allow them to be used by other projects, like the
lorax-composer API server.
