Handle duplicate emails on confirmation and make the confirmation error page nicer

templates/confirmerror.html

@@ -0,0 +1,20 @@
+{% extends "base.html" %}
+
+{% block title %}
+  <title>Confirmation error · Quay.io</title>
+{% endblock %}
+
+{% block body_content %}
+  <div class="container">
+    <div class="row">
+      <div class="col-md-12">
+        <h2>There was an error confirming your e-mail address.</h2>
+
+        {% if error_message %}
+          <div class="alert alert-danger">{{ error_message }}</div>
+        {% endif %}
+      </div>
+    </div>
+
+  </div>
+{% endblock %}