Bump extract-text-webpack-plugin from 2.1.2 to 3.0.2

Bumps [extract-text-webpack-plugin](https://github.com/webpack-contrib/extract-text-webpack-plugin) from 2.1.2 to 3.0.2.
- [Release notes](https://github.com/webpack-contrib/extract-text-webpack-plugin/releases)
- [Changelog](https://github.com/webpack-contrib/extract-text-webpack-plugin/blob/master/CHANGELOG.md)
- [Commits](https://github.com/webpack-contrib/extract-text-webpack-plugin/compare/v2.1.2...v3.0.2)

package.json

@@ -56,7 +56,7 @@
     "eslint-plugin-standard": "^3.0.1",
     "eventsource-polyfill": "^0.9.6",
     "express": "^4.14.1",
-    "extract-text-webpack-plugin": "^2.0.0",
+    "extract-text-webpack-plugin": "^3.0.2",
     "file-loader": "^1.1.5",
     "friendly-errors-webpack-plugin": "^1.1.3",
     "html-webpack-plugin": "^2.28.0",

yarn.lock

@@ -306,6 +306,12 @@ async@^2.1.2, async@^2.1.5:
   dependencies:
     lodash "^4.14.0"
 
+async@^2.4.1:
+  version "2.6.0"
+  resolved "https://registry.yarnpkg.com/async/-/async-2.6.0.tgz#61a29abb6fcc026fea77e56d1c6ec53a795951f4"
+  dependencies:
+    lodash "^4.14.0"
+
 async@~0.9.0:
   version "0.9.2"
   resolved "https://registry.yarnpkg.com/async/-/async-0.9.2.tgz#aea74d5e61c1f899613bf64bda66d4c78f2fd17d"
@@ -2456,12 +2462,12 @@ extglob@^0.3.1:
   dependencies:
     is-extglob "^1.0.0"
 
-extract-text-webpack-plugin@^2.0.0:
-  version "2.1.2"
-  resolved "https://registry.yarnpkg.com/extract-text-webpack-plugin/-/extract-text-webpack-plugin-2.1.2.tgz#756ef4efa8155c3681833fbc34da53b941746d6c"
+extract-text-webpack-plugin@^3.0.2:
+  version "3.0.2"
+  resolved "https://registry.yarnpkg.com/extract-text-webpack-plugin/-/extract-text-webpack-plugin-3.0.2.tgz#5f043eaa02f9750a9258b78c0a6e0dc1408fb2f7"
   dependencies:
-    async "^2.1.2"
-    loader-utils "^1.0.2"
+    async "^2.4.1"
+    loader-utils "^1.1.0"
     schema-utils "^0.3.0"
     webpack-sources "^1.0.1"