Added QAbstractListModel for storing stations list.

Search results and favorites will derive from it.

Also added Station struct which represents a station. See #62 for details.
Changed FahrplanFavoritesManager and added StationSearchResults clas:

- renamed FahrplanFavoritesManager into Favorites;
- removed duplicate code from Favorites and made it child of
  StationsListModel;
- added StationSearchResults class that will represent search for station
  results;
- removed mainwindow.cpp from being built on BlackBerry 10.

WARNING: Broken state!
Integrated StationSearchResults into Fahrplan.

WARNING: UI is in the broken state.
[N9,SYM,BB10] Added BusyLabel component.
[N9,SYM,BB10] Have only one instance of FahrplanBackend component.

Defined in MainPage.qml and visible in other pages as a "global" variable.

Same with InfoBanner, but it's defined in main.qml.
[N9,SYM,BB10] Adapted UI to use the new list model approach.
Pass Station instead of QString when searching for journey and timetable.

See #24 for details.
[HAFAS XML] Use station ID when searching for journey and timetable.

See #24 for details.
[HAFAS Binary] Use station ID when searching for journey.

See #24 for details.

As a side effect, fixes #30 - bahn.de backend is not working for (at least
one) particular station.