Add sprunge script for pastebinning with Tor.

 * Also sets our user agent to that of Tor Browser Bundle.
 * To use, do: "$ echo 'testing 1 2 3' | sprunge"
 * Assumes that our Tor SocksAddress is 127.0.0.1:59050.
Add semaphore wrapper script "only".

 * For calling other commands/scripts only if they are not already running.
Add git serverside hook for checking GPG signatures on commits.

 * Checks that the signature on a git commit made with "$ git commit -S " has a
   good signature from one of the long keyids in a set of allowed repository
   collaborators.