0.0.4 client recording

Created by: bmarv

clients can grab their webcam-stream and display them in their Frontend during runtime, after they have been prompted to allow the usage of the webcam and microphone. The recording of each client starts from the moment the host invokes the broadcast-start, from this point on the clients could theoretically make music or other stuff that will be recorded. When the host triggers the broadcast-stop, the client-recordings will be stopped immediately and they will be prompted to save the resulting video-file (in firefox; chrome saves the file automatically in downloads). Afterwards it is planned that the clients can upload the video using the websocket-technology, where further implementations for that have not happened so far. For the recording, RecordRTC is the used dependency.