Refer to LICENSE, rather than README
Rename README to README.rst

This is so the README on Github will look pretty.
Code quote *args and **kwargs

This fixes a documentation error, as ``*`` looks like the start of
a reStructuredText emphasis.
Be clear on when HasLength passes or fails

Piggy-backing the change on to other doc fixes.
Merge pull request #3 from jml/doc-fixes

Fix API documentation problems
Merge pull request #1 from jml/rename-readme

Rename README to README.rst