added listing of kinect2 devices. added check for validity of provided serial.
added listing of kinect2 devices.
added check for validity of provided serial.

lakehanne/iai_kinect2,OpenPTrack/iai_kinect2,personalrobotics/iai_kinect2,OMARI1988/iai_kinect2,irazr/iai_kinect2,personalrobotics/iai_kinect2,MRASL/iai_kinect2,code-iai/iai_kinect2,cmcmurrough/iai_kinect2,ShibataLab/iai_kinect2,lakehanne/iai_kinect2,code-iai/iai_kinect2,wkentaro/iai_kinect2,pammirato/iai_kinect2,pammirato/iai_kinect2,wjchen84/iai_kinect2,cmcmurrough/iai_kinect2,code-iai/iai_kinect2,jsr38/iai_kinect2,jsr38/iai_kinect2,ShibataLab/iai_kinect2,irazr/iai_kinect2,wjchen84/iai_kinect2,OpenPTrack/iai_kinect2,braincorp/iai_kinect2,ethz-asl/kinect2-ros,wkentaro/iai_kinect2,braincorp/iai_kinect2,ethz-asl/kinect2-ros,OMARI1988/iai_kinect2,MRASL/iai_kinect2