doc fix
Merge branch 'grad' of github.com:epfl-lts2/pyunlocbox into grad

Conflicts:
	doc/tutorials/cs_dr_convergence.pdf
	doc/tutorials/cs_dr_results.pdf
	doc/tutorials/cs_fb_convergence.pdf
	doc/tutorials/cs_fb_results.pdf
	doc/tutorials/simple_convergence.pdf
	pyunlocbox/demos/demo_douglas_rachford.py