Minor refactoring of uxperf workloads

Delete saved images during teardown of googlephotos workload.  Refactor
selectPhoto helper method in googlephotos and add pause in Multiapp
workload for stability. Includes minor fixes.

wlauto/workloads/multiapp/uiauto/src/com/arm/wlauto/uiauto/UiAutomation.java

@@ -28,6 +28,7 @@ public class UiAutomation extends UxPerfUiAutomation {
 
         confirmAccess();
         googlephotos.dismissWelcomeView();
+        googlephotos.selectWorkingGallery();
 
         // select the first photo
         googlephotos.tagPhoto(0);
@@ -90,6 +91,8 @@ public class UiAutomation extends UxPerfUiAutomation {
         shareUsingApp("Skype");
         skype.handleLoginScreen(loginName, loginPass);
         confirmAccess();
+
+        sleep(10); // Pause while the app settles before returning
     }
 
     private void sendToSkype() throws Exception {