Fix sig violation detection

Especially for posts with centred images
Weeks have 7 days in them, not 14
Check browsing options on report page
Use the Firefox SDK tarball instead of the git repo

addons.mozilla.org will reject packages uploaded using the git version.
Remove comment in Chrome/manifest.json

Confuses the Chrome store
Remove Chrome update URL

Disallowed by the Chrome store
Add comment explaining the use of unsafeWindow
Add build/chrome-store-upload.zip to the Makefile
Add website permissions for Chrome/manifest.json in Makefile
Clean Chrome and Firefox directories in `make clean`
Merge remote-tracking branch 'BabelExt/master' into HEAD

Conflicts:
	Chrome/manifest.json
	lib/config.txt
Updated version number to 2.2

Actual command: ./release.sh 2.2
Fix edit time on report page for posts with signatures
Don't overwrite the message on sencond (and later) infraction pages
Updated version number to 2.3

Actual command: ./release.sh 2.3
Link to the Chrome store in build/index.html