PhantomJS for everybody - closes #24 and #26

This commit does the following:

- removes name mapping for windows
- adds the `phanomjs` module to the dependencies, which will download the phantomjs binary - ready for usage
- it filters out all other `phantomjs` paths on Windows and only returns this one
- for non-Windows OS-es (function `checkOthers()` it checks to see if the name is `phantomjs` so that it doesn't need to run spawn to get its info)

I've checked this on both Windows and Linux and it works. I'm not at home atm, or else I would have checked it on OSX as well, but I'm almost sure it works fine there as well.

Let me know what you think.
This doesn't seem to be future-proof. If something changes in the future we're gonna have to add another condition here - not good. I'd leave a map, just remove all unnecessary cases, then if no mapping is found, we should proceed with `browser.name`.