feat(baumeister): Update ESLint, plugins and shared configs to their latest versions

BREAKING CHANGE: The updates of ESLint, plugins and shared configs to their latest versions might break your build since new versions have introduced new rules which might introduce linting errors in your code base.

Tip: Run `npm run eslint:fix` to see which errors are autofixable. And remenber to turn off rules in /.eslintrc.json in case you find them too opinionated.

Author: mischah

app/templates/_package.json

@@ -75,7 +75,7 @@
     "promise-polyfill": "^8.1.0"
   },
   "devDependencies": {<% if (templateProps.projectType === 'spa') { %>
-    "eslint-plugin-react": "^7.7.0",
+    "eslint-plugin-react": "^7.12.4",
     "@babel/plugin-transform-react-jsx": "^7.3.0",
     "@babel/plugin-proposal-class-properties": "^7.3.3",<% } %>
     "@babel/core": "^7.2.2",
@@ -99,13 +99,13 @@
     "css-loader": "^2.1.0",
     "cssnano": "^4.1.8",
     "del-cli": "^1.1.0",
-    "eslint": "^4.19.1",
-    "eslint-config-baumeister": "^1.0.2",
-    "eslint-config-xo": "^0.20.1",
-    "eslint-plugin-filenames": "^1.2.0",
-    "eslint-plugin-import": "^2.10.0",
+    "eslint": "^5.13.0",
+    "eslint-config-baumeister": "^1.2.0",
+    "eslint-config-xo": "^0.26.0",
+    "eslint-plugin-filenames": "^1.3.2",
+    "eslint-plugin-import": "^2.16.0",
     "eslint-plugin-security": "^1.4.0",
-    "eslint-plugin-unicorn": "^4.0.2",
+    "eslint-plugin-unicorn": "^7.1.0",
     "file-loader": "^3.0.1",
     "globby": "^8.0.1",
     "husky": "^0.14.3",