Adding missing copyright, spaces to tabs in .go files

a bunch of silly tabs+spaces tweaks, easiest to review using https://github.com/pdehaan/wmf/compare/spaces2tabs?expand=1&w=0

1. Added missing copyright header in [src/mozilla.org/util/aws.go](https://github.com/jrconlin/wmf/blob/master/src/mozilla.org/util/aws.go)
2. Noticed a few files had mixed tabs and spaces, so I converted 4 leading spaces to tabs for consistency (it seemed most files were tab-dominant). I only looked at the .go files, so not sure if we care enough to go through the .html, .js, .py files and also use tabs (or whatever).