Fix wercker.yml.

Author: ksoichiro

wercker.yml

@@ -13,7 +13,9 @@ build:
           echo $ANDROID_UPDATE_FILTER
           echo $ANDROID_NDK_HOME
     - android-sdk-update:
-        filter: tools,platform-tools,android-21,android-22,android-23,build-tools-23.0.2,extra-android-support,extra-android-m2repository
+        filter: tools,platform-tools
+    - android-sdk-update:
+        filter: android-21,android-22,android-23,build-tools-23.0.2,extra-android-support,extra-android-m2repository
     # A step that executes `gradle build` command
     - script:
         name: run gradle