Add the ScopedModel Counter sample (#41)

Adds sample app that mimics the beloved starter app, but with ScopedModel for state management.

Contains a smoke test and is set up to run it in travis_script.sh.

scoped_model_counter/pubspec.yaml

@@ -0,0 +1,24 @@
+name: scoped_model_counter
+description: >
+  The starter Flutter application, but using ScopedModel to manage state.
+
+version: 1.0.0+1
+
+environment:
+  sdk: ">=2.0.0-dev.68.0 <3.0.0"
+
+dependencies:
+  flutter:
+    sdk: flutter
+
+  scoped_model: ^1.0.1
+
+  cupertino_icons: ^0.1.2
+
+dev_dependencies:
+  flutter_test:
+    sdk: flutter
+
+
+flutter:
+  uses-material-design: true