When IPA package is being updated, some of the configuration files
are also updated. Sometimes it may be useful to store upgrade meta
information for next package upgrades. For example an information
that some config file was already updated and we don't want to
update it again if user purposedly reverted the change.
This patch adds a new StateFile in /var/lib/ipa/sysupgrade which
is capable of holding this information. New sysupgrade.py module
was created to provide simple API to access the upgrade state
information.
