Update metadata in setup.py

- download url is mostly deprecated since PEP 470 has deprecated external
  hosting.

- we can also avoid providing a url for the licence

setup.py

@@ -897,8 +897,7 @@ def compiler_has_flags(compiler, flags):
     maintainer='PyTables maintainers',
     maintainer_email='pytables@pytables.org',
     url='http://www.pytables.org/',
-    license='http://www.opensource.org/licenses/bsd-license.php',
-    download_url="http://sourceforge.net/projects/pytables/files/pytables/",
+    license='BSD 2-Clause',
     platforms=['any'],
     ext_modules=extensions,
     cmdclass=cmdclass,