added require 'pry-nav' to cli.rb, fixes #9
added require 'pry-nav' to cli.rb, fixes #9

* Pry loads the cli.rb for a plugin at startup, rather than at Pry.start().
By adding this file we ensure that pry-nav's monkeypatch applies without requiring an additional
require 'pry-nav' by the user.

nixme/pry-nav