Fix: Move the library prop-types to dependencies

The package is used in the general js code and should not be a dev dependency.

fix #38

Author: Markus Günther

package.json

@@ -22,7 +22,8 @@
   ],
   "dependencies": {
     "hoist-non-react-statics": "^3.0.1",
-    "invariant": "^2.2.4"
+    "invariant": "^2.2.4",
+    "prop-types": "^15.6.2"
   },
   "devDependencies": {
     "@types/react": "^16.4.7",
@@ -44,7 +45,6 @@
     "jest": "^23.4.2",
     "jsdom": "^12.0.0",
     "prettier": "^1.14.0",
-    "prop-types": "^15.6.2",
     "react": "^16.4.2",
     "react-dom": "^16.4.2",
     "rimraf": "^2.6.2",