Adds missing viewBox attribute to SVG flags with Scour

Some renderers, Internet Explorer in particular, has trouble figuring out the correct size of an SVG without the viewBox attribute. This cleans up and replaces width and height attributes with the viewBox attribute where possible using Scour. One flag in particular has not been updated, simply because it uses very strange width/height attributes and would require manual editing/cleanup. This is Armenias flag.