ENH: add robot

The beamline also has a sample changing robot. The robot's API is [here](https://github.com/NSLS-II-XPD/ipython_ophyd/blob/master/profile_collection/startup/85-robot.py).

In terms of implementation, I expect that we'll need to take in an optional kwarg for the robot object, and then the detector will get the sample information from the robot to determine which image to display.