fix(gestures): export gesture config as part of core (#488)

Author: kara

src/core/core.ts

@@ -4,3 +4,6 @@ export * from './rtl/dir';
 // Portals
 export * from './portal/portal';
 export * from './portal/portal-directives';
+
+// Gestures
+export * from './gestures/MdGestureConfig';