Added pixeRatio, deleted matchmedia script

matchmedia is no longer needed, pixelRatio easily via
window.devicePixelRatio

Signed-off-by: Andreas Geibert <ageibert@cemico.de>
Merge branch 'master' of github.com:geibi/pictureserve

Conflicts:
	pictureserve.js

Signed-off-by: Andreas Geibert <ageibert@cemico.de>