fix installing from a git clone , windows

When cloning from a windows machine hardlinks are converted to text file, the text being the path to the real file.
There are at least three files that are hardlinked in the nikola repo and setup.py install will see those files with wrong content.
In particular nikola build for the demo site would fail.

I propose a small change in setup.py : copy the intended content over the git-hardlink-makers, see the diffs.

PD: while I modified and tested my local clone (all ok) , I was unable to push to the forked repo, so copy-pasted from the github web interface, just saying because indentation and gremlins...