Merge pull request #1 from blackcompe/master

Merging pull request/
added image files, updated manifest, fixed tabbing
image files are icons. manifest references icons.
background.js had incorrect tabbing
moved background.html to /html/
small spot fixes and refactoring
removed implicit global declaractions, made local
changed some names to follow style guidelines
changed inner variables to not conflict with outer
1. Fixes #4