Some whitespace cleanup

My editor likes to make lines with trailing whitespace red, so I'd better fix that to keep sane.

By the way, the first and last lines of [this range](https://github.com/biocore/bipy/blob/master/bipy/core/tests/test_distance.py#L435-L448) have a trailing space. If we can remove those then `pep8 bipy` passes. Currently we run `pep8 --ignore=W` which must have some kind of bug because it raises errors for stuff that isn't an error when not ignoring warnings (!).

In emacs this can be automated by adding `(add-hook 'before-save-hook 'delete-trailing-whitespace)` to `.emacs`.

This shouldn't mess with any of the files being modified/added in the other PRs.