Add a protocol & CaptureDevice that read ivf files (raw vp8 files) for the vp8 frame.
A custom MediaDevice is also added for convenience.
Add a protocol & CaptureDevice that read rtpdump files to re-send
the payload of the rtp packet recorded in the file.

You can create rtpdump file from wireshark (see comments in code).

Also add a custom MediaDevice for convenience.
Add a protocol & CaptureDevice that generate RGB frame creating a fading from
white to black to white etc.

Also add a custom MediaDevice for convenience (create a CaptureDevice with
different dimension or/and framerate than default ones).