Improve texts throughout the app

Mysterious acronyms are not very clear, lets reserve the term EIP for internal usage and call it "Encrypted Internet" to the user. In places where we want to be more verbose, maybe we can say Encrypted Internet (VPN) or Encrypted Internet Proxy. My worry is that "proxy" might be confusing to novice users.

(from redmine: created on 2013-05-31, closed on 2013-06-17, blocks #2757 (closed), blocks #2762 (closed))