Add support for loadFileUrl (and style mixups)
Renamed CDVWebViewOperationsDelegate to CDVWebViewProxy (plus uncrustify style fixups)
Modularized CDVWebViewPreferences.
Cleaned up CDVWebViewProxy code for redundancies.
Separate the WebViews into plugins, prep for plugin breakout (plus style mixups)
Removed WebKit.framework dependencies in core files, WKWebView and UIWebView are fully pluginized. WKWebView will need a local web server for use on device currently (Simulator is fine)
Removed the WKWebViewEngine. The plugin now exists in the cordova-plugins repo.
Removed the CordovaWebViewEngine preference. This will be installed by the wkwebview-engine plugin.
Fixed the failing unit-tests, plus style fix-ups.

Note that some of these tests, like the User-Agent tests, are specific to UIWebView and are treated as such. The StartPage test should also work for WKWebView, and should be changed to support that as well, although it is not trivial.
Use default web view engine (UIWebView) if external web engine is not supported in the current runtime version, or it doesn't conform to the protocol.
Remove deleted preference from config.xml in the test app.
Changes in CDVWebViewEngineProtocol.

Removed loadFileURL (implicit handling in loadRequest), and changed the return signatures for loadHTMLString and loadRequest.
Changes in CDVUIWebViewEngine for new changes in CDVWebViewEngineProtocol.

Made protocol implementation explicit, instead of forwarded (removed pragma). Style fix-ups.