media-fonts/adobe-sourcehansans: rename to source-han-sans

This is a Open Source project CALLED source-han-sans
do not add Adobe or somethings like that since it is not
the commercial edition.
media-fonts/source-han-sans: improve ebuild, add fontconfig.
media-fonts/source-han-sans: fix unnecessary longdescription in metadata.xml
media-fonts/source-han-sans: add me to the maintainers list.