Merge pull request #21 from tjguk/master

Merge Tim Golden's improvements to _scandir.c
Remove tests referencing .dirent (no longer exists).
Draft version of the PEP (only Abstract filled out so far).
Fix benchmark.py on Python 3.
Issue 10: Note which Python versions scandir is supposed to support.
Bump up version number for PyPI release.
Remove some printf debugging in the Linux version.
Per @moloney's, fix call to os.symlink() for Python 2 compatibility (see https://github.com/moloney/scandir/commit/1f15198b045fea67fe453919dbfa5bdaf6829a52)
Made package upload to PyPI.
Moved tests/ dir to test/ to be consistent with how "setup.py sdist" thinks.
Updated CHANGES.txt for v0.4
Yesterday's work on the PEP.