Fixed selecting required packages (openssh, SuSEfirewall2) in case of default configuration + minimal sw selection

- Packages are now requested always
- Opens/closes ports as requested by user
- bnc#893126
- includes a little refactoring
- no test case, that require to put everything into lib/network (in TODO)
- tested in production

It actually demonstrate, that libyui silenty ignore unknown symbols, which is wrong and in ideal case we should switch it to raise exception like "unknown id". In such case it will be same as constant.