SLE12 support for SLE11-SP3 

- Added support for SLE12 products
- Tested in SLES11-SP3
- 2.17.7

Found and fixed some additional bugs:

- Write FTP firewall port config
- Install `nfs-kernel-server` package when NFS server is selected (missing in minimal system)
NTH: Returning list of strings is not a good idea as it brings another level of complexity. You need to read the whole function to understand what it does. Maybe return a `map`?

NTH: Better function name: do not name it by what it `does` but what it `returns`

NTH+: Better function description