Logger: Make it work with new SailfishSDK release (Alpha4)

For some reason fprintf does not display logs reliably in new SDK
release.

This patch also disables log cache until a proper UI is implemented for
viewing such logs.
Cleanup and improve application cover pages.
Update default english translation.
Account: Handle situation where YouTube auth has been disabled.

In the current setup the user can go from Account page to Settings and
disable YouTube authorization. In such case the Account page should not
be possible to reach. Unfortunately it can be still on the page stack.
In such case fall back to the video categories page instead.
Settings: Handle YouTube permission request canceling on failures.

Previously it was possible to cancel YouTube OAuth2 page and still have
the authorization check box selected.
YTOauth2: Improve notification handling

Instead of using global network error notification from YTPlayer.qml use
local ones.
Version 0.2.0.