Resolve dependencies when installing from pypi

I just installed wbdata via pip and the required `decorator` package was not automatically installed. I changed the setup script to correctly resolve and install all dependencies listed in requirements.txt

I also added .egg-info and some more patterns to .gitignore, that you usually don't want in a Python project, these patterns come from https://github.com/github/gitignore/blob/master/Python.gitignore