Update ember-web-app to v2.3.0

ember/package.json

@@ -65,7 +65,7 @@
     "ember-svg-jar": "^0.12.0",
     "ember-test-selectors": "^0.3.8",
     "ember-truth-helpers": "^2.0.0",
-    "ember-web-app": "^2.0.0",
+    "ember-web-app": "^2.3.0",
     "eslint-config-simplabs": "0.4.0",
     "eslint-plugin-ember": "^5.0.3",
     "eslint-plugin-mocha": "^4.11.0",

ember/yarn.lock

@@ -3621,15 +3621,17 @@ ember-weakmap@^3.0.0:
     debug "^3.1.0"
     ember-cli-babel "^6.3.0"
 
-ember-web-app@^2.0.0:
-  version "2.0.0"
-  resolved "https://registry.yarnpkg.com/ember-web-app/-/ember-web-app-2.0.0.tgz#56c825d835fa9c3f6cb7901a5687c50c91341edf"
+ember-web-app@^2.3.0:
+  version "2.3.0"
+  resolved "https://registry.yarnpkg.com/ember-web-app/-/ember-web-app-2.3.0.tgz#201e9c01aae12945582602a4cb91329605280f48"
   dependencies:
     broccoli-asset-rev "^2.5.0"
-    broccoli-plugin "^1.3.0"
+    broccoli-caching-writer "^3.0.3"
+    broccoli-merge-trees "^2.0.0"
     ember-cli-babel "^6.0.0"
     object-assign "^4.1.1"
     web-app-manifest-validator "^1.0.0"
+    xmlbuilder "^9.0.4"
 
 ember-wormhole@^0.5.2:
   version "0.5.2"
@@ -8352,6 +8354,10 @@ xdg-basedir@^3.0.0:
   version "2.0.1"
   resolved "https://registry.yarnpkg.com/xml-name-validator/-/xml-name-validator-2.0.1.tgz#4d8b8f1eccd3419aa362061becef515e1e559635"
 
+xmlbuilder@^9.0.4:
+  version "9.0.4"
+  resolved "https://registry.yarnpkg.com/xmlbuilder/-/xmlbuilder-9.0.4.tgz#519cb4ca686d005a8420d3496f3f0caeecca580f"
+
 xmldom@^0.1.19:
   version "0.1.27"
   resolved "https://registry.yarnpkg.com/xmldom/-/xmldom-0.1.27.tgz#d501f97b3bdb403af8ef9ecc20573187aadac0e9"