Clean up sample config.
Added link to qunit-promises to the list of plugins

[qunit-promises](https://github.com/bahmutov/qunit-promises) makes it easy to check the resolved / rejected promises, including values.
Plugins: Themes were moved to their own repos, make a new section for those
1.12.1
Add section on writing custom assertions
Add links to relevant API pages
Cookbook: Remove unnecessary paragraph in 'custom assertions' section.

The description above is accurate, we're not promoting globals anymore.
Cookbook: testrunner.js is now qunit.js, which has eight assertions.
Resources: Update the QUnit copy to v1.12.0
1.12.2
Plugins: Added link to qunit-once plugin

Closes gh-56
1.12.3
Cookbook: Replace broken noglobals example with local copy

Fixes #30
1.12.4
index: changed CDN hosting company
1.12.5
Build: Upgrade to grunt-jquery-content 0.10.11
1.12.6
plugins: removed the div content container
intro examples: removed the id attribute from the li as agreed