Change Tor Browser Bundle to Tor Browser in package strings, download pages, and docs

Now that Tor Browser Bundle is more like a standalone browser and less like a bundle, we should rename it to just "Tor Browser" everywhere. We've done this for the packages names, but the logos, DMG templates, download page, and documentation still call it "Tor Browser Bundle".

We should take an inventory of all the things we need to update, and go at it.