Merge pull request #3 from JonathanTR/01-b-basic-index-page

01 b basic index page
01-c: Include rspec and create spec helper.
01-c: Add Rspec and Capybara for testing.
01-c: Rename groundhog.rb to groundhog_app.rb for clarity.
01-c: Add preliminary test: a get request to the root page should return 200 OK.