created assets folder

moved external stylesheet into assets/css folder
edited CSS file

Finished styling the Med and Low-res versions of the layout. (tablet,
and mobile layouts)
Graphics added

Styles have been updated, graphics added to layout as well.
graphics added
logo image URL typo corrected
Merge branch 'gh-pages' of https://github.com/JayWIlsonJr/Learning_Responsive_WebDesign into gh-pages

Conflicts:
	index.html