Re-orders requires to load right Nokogiri version
Bumps version
Fixes wrongly written _match assertions in unit tests
Fixes wrongly written _match assertions in integration tests and Test class
Ruby 2.0 compatibale via test suite updates.

Switches from test/unit to using minitest directly. Fixes errors in
assert_match assertions (previously papered over by test/unit error
handling). Fixes typos in assert_raises assertions (previously caught
by test/unit stubs).

Makes minitest, vcr, and webmock development dependencies. VCR and
Webmock had been runtime dependencies. Requires minitest >= 5.0.