Add content to README, install.sh.

Add:
	README.md
		-add content to README: list dependencies, provide installation,
		compilation, execution, and cleanup instructions.

	install.sh
		-add shell-script to install any project dependencies (currently the SDL
		library).

	makefile
		-change flag to link SDL library from "-lSDL" to the output of
		"sdl-config --libs"