Redirect python's STDERR to /dev/null

This way if you hit Ctrl-C (which I do constantly) you don't get crashed
Python output.
move remote tracking presentation in zsh
utf8 boilerplate not necessary anymore
move "clean" flag calculation to zsh
only count untracked files at first level

the previous implementation was counting each and every untracked file, even in sub-sub-folder, which could take ages
disable caching by default
add MIT License
unicode and compatibility with Python 3

the code should now run equally well with Python 2 and 3
Merge remote-tracking branch 'justinforce/silent'
See #38
pull the origin