Fix pyqi dependency link

Some versions of setuptools don't support the git+https URL scheme in ```dependency_links```, so ```python setup.py install``` doesn't work (even though ```pip install .``` does work). Updating the link to point to GitHub's .zip archive of latest pyqi master seems to work (with both pip and setup.py installation).
Merge pull request #270 from jrrideout/setuptools-dep-links-fix

Fix pyqi dependency link