Fixed transposition of width and height.

Hi,

I ran pgr_camera_node and it appeared to have width and height transposed:

$ rostopic echo -n1 /pgr_camera/image_raw --noarr
header: 
  seq: 0
  stamp: 
    secs: 1390682470
    nsecs: 993906052
  frame_id: pgr_camera_frame
height: 640
width: 480
encoding: mono8
is_bigendian: 0
step: 640

This change fixes that.

Thanks,
Jim