Avoid using attribute selectors and :not instead of class selectors

It's easier to read and provides better support to those whom have
implemented the old grid with many extra/other classes.
Don't change the width of nested grid12.
Further scope the first class in BP3.
Merge pull request #518 from kabel/grid-selectors

Avoid using attribute selectors and :not instead of class selectors
Merge branch '4.0' of github.com:unl/wdntemplates into image