move physdev definition to render_ifcfg_vlan.
split unset target params in render_ifcfg_network_configuration.
move hw param to other unset.
replace param-speficif arguments with "${@}".
split some part of unset target.
integrate unset params line including onboot.
remove unnecessary code.
define/use IFCFG_NETWORKING_PARAMS.
Merge pull request #51 from hansode/refactor-ifcfg-setup

Refactor ifcfg setup