Allow users to specify qunitjs version

[Krinkle]

Under npm 1.x it loads qunitjs 1.10.0 which is quite old at this point.

Projects like karma-qunit specify a minimum version, thus allowing the final consumer to specify a different version in their package.json. https://github.com/karma-runner/karma-qunit/blob/v0.1.4/package.json:

  "peerDependencies": {
    "qunitjs": "^1.14.0"
  },

Under npm 2.x it interestingly refuses to load 1.10.0 alongside a newer version in some cases, resutling in the following:

npm WARN unmet dependency qunit requires qunitjs@'1.10.0' but will load qunitjs, which is version 1.17.1

.. on a project with:

  "devDependencies": {
    "karma": "0.12.31",
    "karma-qunit": "0.1.4",
    "qunit": "0.7.5",
    "qunitjs": "1.17.1"

[nikolas]

Thanks for looking into this. This is kind of a duplicate of issue #110

[jzaefferer]

Closing as duplicate of #110.