Handle MobileFrontendBeforeDOM hook instead of double parsing

* Removed previous onMinervaPreRender DOM parsing and HTML replacing
* Added onMobileFrontendBeforeDOM handler that uses
formatter->getDoc() to modify DOM object
* For config:showImages==false, optimized execution speed and removed
URL's ?renderZeroRatedBanner=true rewriting
* Removed dead code in external link decoration
* Removed getVersion() call

Change-Id: I8f45e48ea6c3f6860641458c1da544b9067c2477