[Fix #828] Fix completion issues and don't forget project directory in `cider-connect`

  - Add default values to fix `ido-ubiquitous` and standard `completing-read`
  - Look into current project directory for `nrepl-port` files
  - Generalize and rename `nrepl-default-port` -> `nrepl-extract-port`
  - Make sure that ports are always found in the right host (when connecting from
    remote files to localhost, or connection to different remotes than the
    current file's host)
Merge pull request #829 from vitoshka/connect-completion

[Fix #828] Fix completion issues and don't forget current project directory in `cider-connect`