Neotree bindings, PR guidelines, evil-nc, ranger-control contrib

• Neotree normal state local key map (thanks to danielwuz)
• Evil-nerd-commenter is now a package again (24.4 byte compile issue has been resolved upstream)
• Add a pull request guideline (see https://github.com/syl20bnr/spacemacs#pull-request-guidelines)
• guide-key is now displayed in a buffer in graphical environment, seems more stable than the tool tip rendering which can get stuck sometimes
• New contribution layer ranger-control (thanks to trishume)