use generic "Registration Server" in progress message (bnc#875196)

(SCC title does not make sense for SMT registration)

- fixed crash in addon registration (a typo)
- fixed caching the registration URL
- display product names in progess
- fixed "Next" button label in installed system
- 3.1.46
refactor base product label
Merge pull request #68 from yast/progress_fixes

use generic "Registration Server" in progress message (bnc#875196)