CategoryVideoList: Fix cover page
Improve scripts for managing MCC to YouTube i18n region coversion.

YouTube has recently added an API for obntaining a list of supported
localization regions. To make sure all those regions are supported by
YTPlayer create a script which checks the local Mobile Country Code to
YouTube region translation matrix against data provider by Google
Implement dedicated ListModel for handling YouTube list responses.

Currently parsed json data is feed into plain qml ListModel from
javascrtipt code. This has a bad effect for animation smoothnes.
The solution is to use a custom ListModel implementation that can be
populated dynamically from C++ code. The new YTListModel can be
associated with a YTRequest. When such connection is made the request
will automatically append newly fetched data to the model.