Implement per account domain access

Added the possibility for assigning users to an account, providing access to all domains associated with that account automatically.

This makes management easier, especially in installations with lots of domains and lots of managing entities.

The old style per-domain permissions are still there and working as usual. The two methods work perfectly side-by-side and are analogous to "user" (per-domain) and "group" (account) permissions as we know them from Active Directory and such places.

(cherry picked from commit 34fbc634d2848a7f76dc89a03dd8c0604068cc17)

app/templates/admin_editaccount.html

@@ -67,6 +67,21 @@
                         <span class="fa fa-envelope form-control-feedback"></span>
                     </div>
                 </div>
+                <div class="box-header with-border">
+                    <h3 class="box-title">Access Control</h3>
+                </div>
+                <div class="box-body">
+                    <p>Users on the right have access to manage records in all domains
+                        associated with the account.</p>
+                    <p>Click on users to move between columns.</p>
+                    <div class="form-group col-xs-2">
+                        <select multiple="multiple" class="form-control" id="account_multi_user" name="account_multi_user">
+                            {% for user in users %}
+                            <option {% if user.id in account_user_ids %}selected{% endif %} value="{{ user.username }}">{{ user.username }}</option>
+                            {% endfor %}
+                        </select>
+                    </div>
+                </div>
                 <div class="box-footer">
                     <button type="submit" class="btn btn-flat btn-primary">{% if create %}Create{% else %}Update{% endif %} Account</button>
                 </div>
@@ -95,4 +110,9 @@
     </div>
 </div>
 </section>
+{% endblock %}
+{% block extrascripts %}
+<script>
+        $("#account_multi_user").multiSelect();
+</script>
 {% endblock %}