Make Nokogiri version less restrictive

Fixes versioning issues:

    ideal-mollie (>= 0) ruby depends on
      nokogiri (~> 1.4.1) ruby

    capybara-webkit (>= 0) ruby depends on
      nokogiri (1.6.0)
Merge pull request #12 from tijmenb/feature/nokogiri-version

Nokogiri-versie minder pessimistisch
optional report_url argument for method new_order_params
added different argument passing for new_order keeping backwards compatibility in mind
Merge branch 'master' of https://github.com/manuelvanrijn/ideal-mollie
changelog
removed support for ruby < 1.9.2
removed support for ruby < 1.9.2
Merge branch 'features/argument-passing-new_order' of https://github.com/manuelvanrijn/ideal-mollie into features/argument-passing-new_order
also remove ree from travis
Merge pull request #13 from manuelvanrijn/features/argument-passing-new_order

Better way to pass argument for new_order
version bump to 1.0.3
Update README.md