Update Ubuntu setup script.
Update Ubuntu setup script.

- Install qt4-x11 dependencies without asking;
- Install all other packages without asking;
- Install additional dependencies such as flex, libbz2, etc required to
  build WebKit.

aurelien-rainone/qt-pyqt-sdk-builder,aurelien-rainone/qt-pyqt-sdk-builder,zehome/qt-pyqt-sdk-builder,zehome/qt-pyqt-sdk-builder,develersrl/qt-pyqt-sdk-builder,develersrl/qt-pyqt-sdk-builder,aurelien-rainone/qt-pyqt-sdk-builder,naufraghi/qt-pyqt-sdk-builder,zehome/qt-pyqt-sdk-builder,develersrl/qt-pyqt-sdk-builder,naufraghi/qt-pyqt-sdk-builder,naufraghi/qt-pyqt-sdk-builder