Run all Konacha tests on starting Guard.

Quick and dirty change to do run of all tests on Guard startup, as guard-rspec does. 

Not the cleanest solution, but with external processes there seldom is. 

NOTE: I ran into an issue where I had to explicitly add:
  require 'capybara/poltergeist'
in my Guardfile for this to work, but that just might be issues with my local setup.