Add support for multiple graphics cards (GPU's)

Our company's medical applications require 6 monitors to display sensitive patient information for our doctors. To do this, we use at least 2 GPU's to display on all 6 monitors, however, Screen Connect sessions will freeze up or grey screen when we connect to these workstations. Screen Connect support has directed us to only use 1 GPU to solve this issue, which seems to work, but then we lose 2 monitors as our Quadro GPU's only have at most 4 display ports. We will try testing a Display port MST Hub to increase the number of ports, but we are hoping a future release will better support multiple GPU's.