Consider using sensor_msgs/Range for 1D range sensors

[William Woodall]

Currently we have a custom "Proximity" message for our sensors, but we might be able to reuse this common message in stead: http://docs.ros.org/api/sensor_msgs/html/msg/Range.html

[Brian Gerkey]

Stick with the custom message for a binary sensor. If/when we add range sensor, use the standard message.

[Deanna Hood]

https://bitbucket.org/osrf/ariac/pull-requests/53