install_requires tries to install python on python > 3.3

Remove this line as we don't want to install python.
I thought it would only check if it's the right version, in fact it tries to install Python ... (build failing on Travis)

Author: iMichka

setup.py

@@ -17,7 +17,6 @@
       download_url="https://github.com/gccxml/pygccxml/archive/master.zip",
       license="Boost",
       keywords="C++, declaration parser, gccxml",
-      install_requires=["Python>=2.6"],
       packages=["pygccxml",
                 "pygccxml.declarations",
                 "pygccxml.parser",