Rewrite Guard-Konacha to increase performance

Changed the strategy of Guard-Konacha. By updating Konacha to accept a Capybara session and run specific urls, Guard Konacha can use a single Capybara session for all runs. Therefor speeding up the running of tests. The old strategy used running the `konacha:run` rake task, and had to setup a server and capybara session for each run.

In this new strategy, the urls of the tests are visited and listened to using the updated Konacha runner. 

For the new strategy, jfirebaugh/konacha#95 has to be merged first and the new Konacha gem should be released. When that is done, I can update the Gemspec file with the new Konacha version that should be required for this code.