fix: upgrade material-ui from 0.16.7 to 0.20.0

Snyk has created this PR to upgrade material-ui from 0.16.7 to 0.20.0.

See this package in npm:
https://www.npmjs.com/package/material-ui

See this project in Snyk:
https://app.snyk.io/org/arunvishnun/project/318e1af6-781f-4f43-b962-53eb11db0421?utm_source=github&utm_medium=referral&page=upgrade-pr

samples/universal-material-ui/package.json

@@ -42,7 +42,7 @@
     "electrode-server": "^1.0.0",
     "electrode-static-paths": "^1.0.0",
     "lodash": "^4.10.1",
-    "material-ui": "^0.16.4",
+    "material-ui": "^0.20.0",
     "react": "^16.0.0",
     "react-dom": "^16.0.0",
     "react-tap-event-plugin": "^2.0.0",