compat: enable compat suse only, install ifcfg-lo

Added --with-compat allowing to build and install compatibility
features conditionally. Added --with-compat=suse to spec file.
Other types than 'suse' are incomplete, unsupported [L3] and we
install suse specific config files and scripts at the moment.
Install the /etc/sysconfig/network/ifcfg-lo file (fate#316768).
Merge pull request #138 from mtomaschewski/suse-ifcfg-lo

compat: enable compat suse only, install ifcfg-lo