Improve member adding and excluding flow

Allow to exclude a member

Send emails to the member when it's excluded

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

lib/web/templates/email/group_invite.html.eex

@@ -35,7 +35,7 @@
       <tr>
         <td bgcolor="#ffffff" align="left" style="padding: 20px 30px 0px 30px; color: #474467; font-family: 'Roboto', Helvetica, Arial, sans-serif; font-size: 18px; font-weight: 400; line-height: 25px;" >
           <p style="margin: 0;">
-            <%= gettext "%{inviter} just invited you to join their group %{group}", group: @group.name, inviter: @inviter.name %>
+            <%= gettext("<b>%{inviter}</b> just invited you to join their group %{link_start}<b>%{group}</b>%{link_end}", group: @group.name, inviter: @inviter.name, link_start: "<a href=\"#{@group.url}\">", link_end: "</a>") |> raw %>
           </p>
         </td>
       </tr>