python plugin

The plugin adds several aliases for useful python commands.

To use it, add python to the plugins array of your zshrc file:

plugins=(... python)

Aliases

Command	Description
`ipython`	Runs the appropriate `ipython` version according to the activated virtualenv
`pyfind`	Finds .py files recursively in the current directory
`pyclean [dirs]`	Deletes byte-code and cache files from a list of directories or the current one
`pygrep <text>`	Looks for `text` in .py files
`pyuserpaths`	Add --user site-packages to PYTHONPATH, for all installed python versions.