QtQuickApp: Tweak template to enable Meego booster

Add support for the meego booster. This requires
 - Telling qmake to link to right libraries
 - Exporting main method
 - using QApplication, QDeclarativeView objects from cache
 - avoiding QCoreApplication::applicationDirPath()

To keep compatibility, QmlApplicationViewer is still derived from QDeclarativeView.
However, if the app booster is used it merely acts as a proxy to the view from the
cache.

Change-Id: I83e285d9ca3c2cfd86d1711e1fb93c72589ba14d
Reviewed-on: http://codereview.qt.nokia.com/3730


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Alessandro Portale <alessandro.portale@nokia.com>
Reviewed-by: Christian Kandeler <christian.kandeler@nokia.com>