[Distutils] Execute command before pip install

[Jorge Maldonado Ventura]

I need to execute a command automatically when running `pip install` to 
solve https://notabug.org/jorgesumle/boot-em-all/issues/1

I need to do that to compile the translation files. I found that 
overriding the `setuptools.command.install` makes it work with `python3 
setup.py install`, but I want it to work with pip as well. Any advice or 
think I overlooked? Is there a clean or recommended way to do this?

The whole code is free software, so you can check my `setup.py` file. 
The repository can be cloned executing `git clone 
https://notabug.org/jorgesumle/boot-em-all`.