properly symlink firstboot.xml file

(for collecting translatable strings by "make pot")
removed unused testsuite/Makefile.am
removed obsolete BuildRequires

(perl-XML-Writer, sgml-skel, yast2, yast2-installation, yast2-testsuite, yast2-xml)
3.0.1
Merge pull request #4 from yast/cleanup

Cleanup