Check the file existence of application.conf.j2 (#3803)

Since the initial openwhisk release does not package the folder tests, we
need to make sure application.conf.j2 exists in order to copy to the remote
server.
diff --git a/ansible/tasks/writeWhiskProperties.yml b/ansible/tasks/writeWhiskProperties.yml
index 516306b..3951c14 100644
--- a/ansible/tasks/writeWhiskProperties.yml
+++ b/ansible/tasks/writeWhiskProperties.yml
@@ -9,10 +9,17 @@
     src: whisk.properties.j2
     dest: "{{ openwhisk_home }}/whisk.properties"
 
+- name: check if application.conf.j2 exists
+  tags: application
+  stat: path="{{ openwhisk_home }}/tests/src/test/resources/application.conf.j2"
+  register: application
+
 - name: write test's application conf overrides
+  tags: application
   template:
     src: "{{ openwhisk_home }}/tests/src/test/resources/application.conf.j2"
     dest: "{{ openwhisk_home }}/tests/src/test/resources/application.conf"
+  when: application.stat.exists
 
 - name: write whisk.conf template for wskadmin to openwhisk_home
   template: