Update Semaphore configuration

.semaphore/semaphore.yml

@@ -11,7 +11,6 @@ blocks:
         - name: docker build
           commands:
             - checkout
-            - 'git clone --recursive https://github.com/fcwu/docker-ubuntu-vnc-desktop'
             - docker build -t cloud9-ide-vdi .
             - '# Define Version Numbers'
             - DATE=$(date +%y%U)
@@ -26,3 +25,11 @@ blocks:
             - 'docker push $DOCKER_USERNAME/docker-cloud9:latest'
       secrets:
         - name: Dockerhub
+      prologue:
+        commands:
+          - git submodule init
+          - git submodule update
+      epilogue:
+        always:
+          commands:
+            - git submodule deinit --force .