Improvements to the Makefile and new SVG version of the icon
- Add a new SVG version of the icon and install it
- Proper instruction to create a tarball with "make tar"
- Replace broken "make clean" instructions with correct ones
Clarify the license and credits of the icon
Adapt spec file to install the svg icon
Merge pull request #21 from akien-mageia/master

Various Makefile improvements, icon license clarifications and new svg icon