Cleanup

- removed empty `agents/Makefile.am` and unused `testsuite/Makefile.am`
- removed obsolete BuildRequires:
    - doxygen
    - perl-XML-Writer
    - sgml-skel
    - yast2-testsuite
    - yast2-storage
    - yast2-pkg-bindings
    - yast2-packager
Merge pull request #61 from yast/cleanup

Cleanup