Move /email_sent/ to flask endpoint, to allow translation

app/templates/users/email_sent.html

@@ -0,0 +1,25 @@
+{% extends "base.html" %}
+
+{% block title %}
+{{ _("Check Your Email") }}
+{% endblock %}
+
+{% block content %}
+<h1>{{ self.title() }}</h1>
+
+<p>
+	{{ _("We've sent an email to the address you specified.") }}
+	{{ _("You'll need to click the link in the email to confirm it.") }}</p>
+
+<p>
+	<strong>
+		{{ _("The link will expire in 12 hours") }}
+	</strong>
+</p>
+
+<p>
+	<a class="btn btn-secondary" href="/help/faq/#my-verification-email-never-arrived">
+		{{ _("My email never arrived") }}
+	</a>
+</p>
+{% endblock %}