Merge branch 'release/0.4.1' into develop
Corrected copyright in docs
Removed trailing white space.
Python 3.x compatibility refactoring. Fixed doctests.
Also run tests under Python 3.
Correct doctests in docstrings
Merge pull request #6

Need to use wrap `url_str` in unicode to get the README doctests to pass
on my Python 2.7 install.  Without this, you get a mix of bytestrings
and unicode strings returned from the accessors.

Conflicts were just doctests.

Conflicts:
	purl/__init__.py