fixes library resolving issues on debian based distros
removing avformat_free_context
Use avg_frame_rate instead of r_frame_rate

r_frame_rate is "the least common multiple of all framerates in the
stream". It is deprecated and removed in Libav. Using avg_frame_rate
instead, which is the average framerate of the stream.
adding option to list detected opencl devices
adding configuration functionality
help formatting
increasing pyr-scale and winsize defaults to optimize for quality
make main script handle exceptions
fix minor argparse help typos
adding show preview while encoding option
fix import py_motion resolving issue in __init__
set ocl kernel binaries cache path to user home when testing
fixing some help typos
disable prep and mux with subs if using avconv
remove ubuntu from readme