FIX 301 search local project root and put .zeus.sock there

- make sure we always put the zeus socket in the project root, when
  launching zeus
- look for the socket in the project root when trying to connect.
- ProjectRoot is defined as the next directory down with a Gemfile
Merge pull request #365 from sideshowcoder/sub_dir_zeus_sock

#301 search local project root and put .zeus.sock there