MyVideoIE: add rtmp support
Merge pull request #842 - myvideo, rtmp support

@dersphere code, from dersphere/plugin.video.myvideo_de.git
rewritten by @mc2avr
released in the Public Domain by the author
ref: https://github.com/rg3/youtube-dl/pull/842
make rtmpdump inherit the verbose option for debugging
Python 2 compat fixes for MyVideo.de rtmpdump downloads