filter out empty "unknown" SMBIOS entries (bnc#880643)

- fixed running X.org detection
- 3.1.4
code review fixes
removed unnecessary test
Merge pull request #8 from yast/remove_unknown_nodes

filter out empty "unknown" SMBIOS entries (bnc#880643)
mark the summary header text for translation (bnc#889683)

- 3.1.5
Merge pull request #9 from yast/translation

mark the summary header text for translation (bnc#889683)