use latest quinit from npm, remove bundled version

package-lock.json

package.json

test/qunit-2.5.0.css

test/qunit-2.5.0.js

test/test-auto-animate.html

test/test-dependencies-async.html

test/test-dependencies.html

test/test-grid-navigation.html

test/test-iframe-backgrounds.html

test/test-iframes.html

test/test-markdown.html

test/test-multiple-instances-es5.html

test/test-multiple-instances.html

test/test-pdf.html

test/test-plugins.html

test/test-state.html

test/test.html