Adding ETL related files for the appkernels module

Added appkernels.json

- Added the modules.d/appkernels.json file to the file_maps section of
  build.json

Author: ryanrath

build.json

@@ -38,7 +38,8 @@
             "configuration/roles.json": "roles.d/appkernels.json",
             "configuration/setup.json": "setup.d/appkernels.json",
             "configuration/rest.d": "rest.d",
-            "configuration/assets.d": "assets.d"
+            "configuration/assets.d": "assets.d",
+            "configuration/modules.d/appkernels.json": "modules.d/appkernels.json"
         },
         "etc/crond": {
             "configuration/cron.conf": "xdmod-appkernels"