build: added transform-class-properties to fix issue with parcel (#188)

Author: juanmaguitar

.babelrc

@@ -4,6 +4,9 @@
     "stage-2",
     "react"
   ],
+  "plugins": [
+    "transform-class-properties"
+  ],
   "env": {
     "esm": {
       "plugins": [

package.json

@@ -58,6 +58,7 @@
     "react": "0.14.x || ^15.0.0 || ^16.0.0"
   },
   "dependencies": {
+    "babel-plugin-transform-class-properties": "^6.24.1",
     "babel-runtime": "6.x.x",
     "create-react-context": "^0.2.1",
     "popper.js": "^1.14.1",