PLT-6406 Migrate new channel modal to be pure and use redux (#6416)

* Migrate new channel modal to be pure and use redux

* Add component tests

webapp/package.json

@@ -26,6 +26,7 @@
     "object-assign": "4.1.1",
     "pdfjs-dist": "1.7.363",
     "perfect-scrollbar": "0.6.16",
+    "prop-types": "15.5.9",
     "react": "15.4.2",
     "react-addons-pure-render-mixin": "15.4.2",
     "react-bootstrap": "0.30.8",