HTML Data addition to WET 4.0

As per https://github.com/wet-boew/wet-boew/wiki/GC-Semantic-Web-Implementation-Guide the following has been marked up.

* breadcrumb
* mainContentOfPage
* name
* SiteNavigationElement
* dateModified
Adapted a responsive equal height script and converted it to a WET v4.0 plugin.
Build: Only run Sauce with Secure Vars

Minor formatting fixes for the saucelabs task
Merge pull request #3145 from nschonni/v4-saucelabs-guard

Build: Only run Sauce with Secure Vars
Merge pull request #3127 from thomasgohard/plugin-responsive-equalheight

Adapted a responsive equal height script and converted it to a WET v4.0 plugin
Merge pull request #3133 from chrismajewski/v4.0

HTML Data addition to WET 4.0
Prettify:  initial port of v3.x plugin

* Only initializes and runs plugin once, regardless of number of
  `<pre class="prettyprint">` elements on page.
* Exposes `window.prettyPrint()` method to other plugins via
  `prettyprint.wb-prettify` event.