Creates windows friendly ruby scripts and updates readme files

Hey Jeff, take a look at the updated ruby initialization scripts. I've confirmed that the scripts work on my windows box, and added notes to the readme. I also worked on a drush version of themify, but was running into issues so it's not included in this pull request. 

For the time being, it seems fine to just have windows users start guard without themify. See the readme for details that I added about getting that working.

Thanks!
Aaron