made changes so that deviceids of devices should no longer be visible to 3rd parties. deviceid is no longer fowarded to shared_device.html. requests made by both device.html and shared_device.html now use the device's hash rather than its ID. Changed the example button on index.html to link to a shared_device.html using this device's hashkey rather than a device.html using deviceid. added helper method in database_helper.py for looking up a device by its hashkey