Camera names for the DKitty env are causing problems in serialization

[vikashplus]

pytorch/rl#2062

tldr:
['A:trackingZ', 'A:trackingY', 'A:headCam', 'A:tailCam', 'A:leftCam', 'A:rightCam']
The colon in the camera name is causing some issues, I'm not sure what that is. But adding cams = [i.replace("A:", "A_") for i in cams] fix the tests.