* format place_tracker README
* update sentence in README
* sort Dart members, remove unnecessary type declarations
* Run place_tracker on Android and iOS, update project files
* add link to developer preview caveat
* grammar
* update MAINTENANCE
* Add list view to place tracker. Note: map in listTile is not WAI in this commit.
* Remove map from list tiles. Make list tiles tappable (currently editing a place and saving will do nothing if the details screen is pushed from the list view.
* Fix text alignment in list.
* Initial implementation of using an InheritedWidget to maintain data between list and map. Map does not update correctly at this point.
* Use AppModel.update to set the AppState. Add MapConfiguration class to handle map changes based on AppState.
* Don't cache AppState - lookup directly. Extract AppState code into it's own file and add static methods. Address comments from Hans.
* Extract generic AppModel code.
