Finding sphero_ros bugs in jade

[devangel77b]

I'm trying to get sphero_ros to work for a course I am teaching and I found several small bugs in sphero_node stuff getting translated to Python (where one ref says values should be a float from 0. to 1. but the sphero driver python code looks to be trying to get a number between 0 and 255). Also there appears to be a bug where set_back_led is not coded right (tries to call set_back rather than set_back_led).