updated BuildRequires: RNG schema moved to yast2-installation-control

additional cleanup:

- removed .cvsignore, updated .gitignore
- use %yast_controldir RPM macro
- move the *.glade link to Git (allow creating POT from clean Git
  checkout without need to run "make")
- 3.1.2
Merge pull request #12 from yast/yast2-installation-control

updated BuildRequires: RNG schema moved to yast2-installation-control