Change Rat.Str test to match current spec, add related tests and simple test for Rat.norm.
Change Rat.Str test to match current spec, add related tests and simple test for Rat.norm.

zostay/roast,niner/roast,niner/roast,laben/roast,b2gills/roast,dankogai/roast,skids/roast,skids/roast,b2gills/roast,laben/roast,cygx/roast,skids/roast,dankogai/roast,cygx/roast,dankogai/roast,dogbert17/roast,perl6/roast,dogbert17/roast,laben/roast,bitrauser/roast,zostay/roast,zostay/roast,niner/roast,b2gills/roast,bitrauser/roast,cygx/roast