Allow url parameter to set Konacha run mode
Allow reusing sessions and inject new urls

This is needed for tighter integration in Guard-Konacha. This allows a
single Capybara session to handle all guard runs and drastically
increase performance
Add tests for @run_mode
Test acceptence of custom path
Move spec to correct location
Update run_mode param to use inquiry
Merge pull request #95 from matthijsgroen/runner-option

Allow tight integration for Guard-Konacha