issue-129 Update signin/up ui-ux

Getting rid of the netlify widgit and rolling our own, gives us the
flexibility to also add the username into the signup process as well
as allow the user to opt into the newsletter at the same time.

Auth is still netlify, via their "gotrue", we're just handling the more
of it.

web/src/components/LoginModal/LoginModal.stories.js

@@ -0,0 +1,7 @@
+import LoginModal from './LoginModal'
+
+export const generated = () => {
+  return <LoginModal open={true} />
+}
+
+export default { title: 'Components/LoginModal' }