update to material-ui 0.20.2

remove react-tap-event-plugin, as it is not needed anymore.

package.json

@@ -30,7 +30,7 @@
     "iso-639-1": "^1.2.1",
     "languagedetect": "^1.2.0",
     "location-history": "^1.0.0",
-    "material-ui": "^0.17.0",
+    "material-ui": "^0.20.2",
     "mkdirp": "^0.5.1",
     "music-metadata": "^3.1.0",
     "network-address": "^1.1.0",
@@ -38,7 +38,6 @@
     "prettier-bytes": "^1.0.1",
     "react": "^15.4.2",
     "react-dom": "^15.4.2",
-    "react-tap-event-plugin": "^2.0.1",
     "rimraf": "^2.5.2",
     "run-parallel": "^1.1.6",
     "semver": "^5.6.0",