Fix strict mode violations ("arguments" assignment)

Fixed a couple cases where the `arguments` variable was being modified in place. This is a strict-mode violation and can cause problems when trying to use _notevil_ in a browser setting via something like [browserify](http://browserify.org/) or building it into a [web component](https://github.com/component/component).

It might be worth considering wrapping the whole library in a UMD wrapper too, to make it more accessible.

The diff is much easier to view without the whitespace changes; my editor removes trailing spaces at the end of lines: https://github.com/Cecchi/notevil/commit/b6c7a27f16db0f37d8fb226d7e9e2ada458ffec3?w=1