removed XVFB dependency; capybara no longer uses selenium
removed XVFB dependency; capybara no longer uses selenium

mark-craig/engineerswithoutborders,tbrachmann/engineerswithoutborders,tbrachmann/engineerswithoutborders,mark-craig/engineerswithoutborders,tbrachmann/engineerswithoutborders,mark-craig/engineerswithoutborders