fix feed.xml is not included in pypi's package

Very sorry for the last 2 pull request, first is not fix, and second is not very well enough.

After read the source code, I find a easy way to solve this issuse.

here is the issuse:

* feed.xml is not included in pypi's package, while run "python setup.py sdist"
* in pypi's dowload package: https://pypi.python.org/pypi/rutherford/0.7
* It is not include the feed.xml, because setup.py "Installing Package Data" miss a config
* I find this issuse, because one of my project add this lib recently, then the project's Travis CI build error.

how to fix:

* see also: http://svn.python.org/projects/sandbox/trunk/setuptools/setuptools.txt
* this means "include_package_data" should False, because:
* "that are either under CVS or Subversion control, or which are specified by your ``MANIFEST.in`` file."