add a JointLimitsChecker instance in startup.py that is enabled by default
add a JointLimitsChecker instance in startup.py that is enabled by default

fixes #473 but requires that Drake is updated to robotlocomotion/master.

openhumanoids/oh-distro,openhumanoids/oh-distro,openhumanoids/oh-distro,openhumanoids/oh-distro,openhumanoids/oh-distro,openhumanoids/oh-distro,openhumanoids/oh-distro,openhumanoids/oh-distro