ipalib: Fix skip_version_check option
    
    This reverts commit ea7f392bb98c1f1c4558ec5d6e84ee7a7c613474.
    
    The option can be either set in IPA config file or specified as
    'ipa -e skip_version_check=1 [COMMAND]'.
    
    https://fedorahosted.org/freeipa/ticket/4768
    
    Reviewed-By: Martin Basti <mbasti@redhat.com>