Bug 869937 - Redirect all firstrun/whatsnew links to bedrock

WARNING: May require changes to PHP site .htaccess before merging.

This change would redirect all firefox/*/firstrun and firefox/*/whatsnew URLs to bedrock, which would then be dealt with smartly with the view behind the firstrun/whatsnew pages.

Once this is in place, we'll be able to delete approximately 10 billion old files from SVN.