Add small screencast that demonstrates topydo.

Recorded with ttyrec, processed with tty2gif [1], turned into animated
GIF with ImageMagick and then optimized using ezgif.com [2]

TTY recording also included with this commit.

[1] https://bitbucket.org/antocuni/tty2gif
[2] http://ezgif.com/optimize/8f097380ed.gif