updating makefile: updated stan-update to take / instead of -
updating makefile: updated stan-update to take / instead of -

evelynmitchell/cmdstan,stan-dev/cmdstan,evelynmitchell/cmdstan,stan-dev/cmdstan,stan-dev/cmdstan,evelynmitchell/cmdstan,stan-dev/cmdstan,evelynmitchell/cmdstan