add fs-extra to devDeps

package.json

@@ -101,6 +101,7 @@
     "eslint-plugin-ember-internal": "^1.1.0",
     "express": "^4.15.2",
     "finalhandler": "^1.0.2",
+    "fs-extra": "^4.0.1",
     "git-repo-info": "^1.4.1",
     "git-repo-version": "^0.4.1",
     "github": "^0.2.3",

yarn.lock

@@ -2905,6 +2905,14 @@ fs-extra@^2.0.0:
     graceful-fs "^4.1.2"
     jsonfile "^2.1.0"
 
+fs-extra@^4.0.1:
+  version "4.0.1"
+  resolved "https://registry.yarnpkg.com/fs-extra/-/fs-extra-4.0.1.tgz#7fc0c6c8957f983f57f306a24e5b9ddd8d0dd880"
+  dependencies:
+    graceful-fs "^4.1.2"
+    jsonfile "^3.0.0"
+    universalify "^0.1.0"
+
 fs-readdir-recursive@^0.1.0:
   version "0.1.2"
   resolved "https://registry.yarnpkg.com/fs-readdir-recursive/-/fs-readdir-recursive-0.1.2.tgz#315b4fb8c1ca5b8c47defef319d073dad3568059"
@@ -3747,6 +3755,12 @@ jsonfile@^2.1.0:
   optionalDependencies:
     graceful-fs "^4.1.6"
 
+jsonfile@^3.0.0:
+  version "3.0.1"
+  resolved "https://registry.yarnpkg.com/jsonfile/-/jsonfile-3.0.1.tgz#a5ecc6f65f53f662c4415c7675a0331d0992ec66"
+  optionalDependencies:
+    graceful-fs "^4.1.6"
+
 jsonify@~0.0.0:
   version "0.0.0"
   resolved "https://registry.yarnpkg.com/jsonify/-/jsonify-0.0.0.tgz#2c74b6ee41d93ca51b7b5aaee8f503631d252a73"
@@ -6052,6 +6066,10 @@ unique-slug@^2.0.0:
   dependencies:
     imurmurhash "^0.1.4"
 
+universalify@^0.1.0:
+  version "0.1.1"
+  resolved "https://registry.yarnpkg.com/universalify/-/universalify-0.1.1.tgz#fa71badd4437af4c148841e3b3b165f9e9e590b7"
+
 unpipe@~1.0.0:
   version "1.0.0"
   resolved "https://registry.yarnpkg.com/unpipe/-/unpipe-1.0.0.tgz#b2bf4ee8514aae6165b4817829d21b2ef49904ec"