Adds semantic labels to images and modal close button (#56)

* Added semantic labels to images.

* Reverting project file.

* Semantic label for close button.

veggieseasons/lib/widgets/veggie_headline.dart

@@ -49,6 +49,7 @@ class VeggieHeadline extends StatelessWidget {
               borderRadius: BorderRadius.circular(10.0),
               child: Image.asset(
                 veggie.imageAssetPath,
+                semanticLabel: 'An icon showing ${veggie.name}',
                 fit: BoxFit.fitWidth,
               ),
             ),