Remove the "return false;" statements

Fixes the “SyntaxError: Return statements are only valid inside
functions” errors in Safari now that the script is auto-updating.
Include static bookmarklet in readme.md

Now that the bookmarklet file just points to the main tweetbot.js it
should be rather static. So instead of linking people to a raw file,
include the content in the readme.md file itself since that will be the main github page.
Merge pull request #3 from dcwalker/master

Remove the "return false;" statements