This update for mksusecd fixes the following issues:

- Extended help text and added some small fixes
- Fix choosing an add-on name
- Be less restrictive when generating add-on aliases
- Support creating add-ons on the target iso (boo#991935)
- Catch error when we fail to unpack squashfs images
- Handle modules.order and modules.builtin when updating a kernel
- tw support: Also sign image files
- Sanitize function that removes files from iso
- Remove tumbleweed images in 'micro' format
- Create missing 'content' file
- Adjust list of specially handled initrd modules
- Add hashes for license and control file
- Support uncompressed initrd (boo#957847)