Improve docstrings
Rename Leiningen tests

With the namespace `leiningen.whitespace-linter-test` Leiningen expects
the test file to implement a task.

To prevent the test files from being picked up as a custom Leiningen
task I'm moving the test within our `whitespace-linter` namespace.
Merge pull request #3 from listora/tidy-up

Tidy up before release