Update README.markdown

[bootstraponline]

I started using this gem in a project for work and encountered a few Why The Failure moments.

• The parallel feature completely breaks if there's an error and no solution for terminating the zombie processes is provided. I've updated the wiki with a one line command that resolves this issue.
• The syntax used in the readme is not valid Ruby.
• The syntax in the readme is inconsistent with the sauce_helper.rb generated by rake sauce:install:spec
• The swappable sauce link is broken
• The gem always errors with Exception occured: uninitialized constant Sauce::RSpec::Spec when used from the Rakefile. The gem should be fixed however requiring bundler works around the issue.

I've fixed or added work arounds for these issues in this PR.

[bootstraponline]

Travis CI failed because the sauce_ruby build is broken and the dependencies are outdated. I've opened an issue for that. #308