Fix crashes found after Qt5 change

There were a few things that caused sysmgr to crash on startup:
- uninitialized pointer in DockModeMenuManager
- DockModeMenuManager::dockAppContainer() was called before the
  pointer it returns had been initialized
- static QFont initializations caused crashes in PageTabBar,
  LabeledButton, PixButton, Icon, HorizontalLabeledDivider
  and TextBox

Open-webOS-DCO-1.0-Signed-off-by: Teppo Pennanen <teppo.pennanen@palm.com>

Change-Id: Ib2f7c04cc77a61d59696b10122065c57fc5fe3d2
Merge "Fix crashes found after Qt5 change" into unstable