Some starter code

Added a `.gitignore` file to ignore some generic system files.

Also added some starter code for style tweaks (just makes stuff wider), and page action, options, and background scripts (don't mind the icons, they're from another of my projects, but it's handy to have all the right sizes there). This PR includes PR https://github.com/Hackathon-Hackers/chrome-extension/pull/1.