Update dependencies to be less strict

Author: Floriferous

package.json

@@ -36,7 +36,7 @@
     "webpack-dev-server": "1.14.1"
   },
   "dependencies": {
-    "prop-types": "15.5.10",
-    "create-react-class": "1.0.0"
+    "prop-types": "^15.6.0",
+    "create-react-class": "^1.0.0"
   }
 }