Added new images for the system processes

	modified:   2-thesis/src/system.tex
	modified:   2-thesis/thesis.tex
	new file:   img/challenge.eps
	new file:   img/challenge.graphml
	new file:   img/challenge_2.graphml
	new file:   img/circle.graphml
	new file:   img/sign-in.graphml
	new file:   img/sign_in.eps
	new file:   img/sign_in.graphml
	new file:   img/sign_in_2.eps
	new file:   img/sign_in_2.graphml
	new file:   img/sign_in_3.eps
	new file:   img/sign_in_3.graphml
	new file:   img/sign_up.eps
	new file:   img/sign_up.graphml
	new file:   img/testing.graphml