fix: package.json to reduce vulnerabilities

The following vulnerabilities are fixed with an upgrade:
- https://snyk.io/vuln/SNYK-JS-DEBUG-3227433

Author: snyk-bot

package.json

@@ -38,9 +38,9 @@
     "chalk": "1.1.3",
     "cross-spawn": "4.0.0",
     "css-loader": "0.23.1",
-    "eslint": "3.1.1",
+    "eslint": "4.7.0",
     "eslint-loader": "1.4.1",
-    "eslint-plugin-import": "1.10.3",
+    "eslint-plugin-import": "2.6.1",
     "eslint-plugin-react": "5.2.2",
     "extract-text-webpack-plugin": "1.0.1",
     "file-loader": "0.9.0",