this options are also settable by config
allow to have installsystems niced before launch action

python-psutil minimun version is 0.2.1 to support set_ionice

old command line option are still present but no more in config file
this allow to override easily on command line config parameters

Image are not crawled anymore in all repositories by default
You needs to specify a list of repo to look in

This allow displaying to be done without coloration