chore(package): update react-modal to version 1.7.7

Closes #311

https://greenkeeper.io/

package.json

@@ -50,7 +50,7 @@
     "postcss-simple-vars": "3.1.0",
     "react": "15.4.2",
     "react-dom": "15.4.2",
-    "react-modal": "1.7.3",
+    "react-modal": "1.7.7",
     "react-redux": "5.0.3",
     "react-style-proptype": "2.0.2",
     "react-tabs": "0.8.2",