slimerjs 0.8.2 (new formula)

In contrast to #22323, this does not install any binary, because it's based on [SlimerJS's Lightweight Edition](http://docs.slimerjs.org/current/installation.html#the-lightweight-edition), which doesn't include the bundled binary of Mozialls XULRunner. The core of SlimerJs is written in shell, js, css and xul and communicate either with a local Mozilla Firefox or Mozilla XULRunner install.
In this Version of the Formula it requires, that you have Firefox (or XULRunner if you prefer the more difficulty way) installed on your mac and have to set the `SLIMERJSLAUNCHER` environment variable to point to it.
The next step would be to add a Formula, which builds Mozillas XULRunner from source, which could be an recommended or optional (have to discuss this) dependency of this formula.

Edit: add removal of .bat file