Add automatic installation of dependencies to setup.py.
Add automatic installation of dependencies to setup.py.

 * ADD function get_requirements() to setup.py file, for parsing the
   requirements.txt file and installing the dependencies specified there. This
   allows us to keep one place for keeping track of dependencies, regardless
   of whether we are installed from a source distribution (git or a tarball)
   or with pip.

pagea/bridgedb,mmaker/bridgedb,wfn/bridgedb,wfn/bridgedb,pagea/bridgedb,mmaker/bridgedb