[Postfix] Allow to set and override a relayhost per mailbox

[Web] Replace recycle icon with trash (this one made me a bit sad)
[Web] Various small fixes
[Web] Allow or disallow a domain admin to change relayhost settings (default is off, as previous default)

data/web/css/build/008-mailcow.css

@@ -76,7 +76,6 @@
   font-size: inherit;
 }
 .icon-spin {
-  font-size: 1.0rem;
   animation-name: spin;
   animation-duration: 2000ms;
   animation-iteration-count: infinite;

data/web/css/site/edit.css

@@ -40,4 +40,8 @@
 .input-group-addon-xmpp {
   background-color: #fff;
   border: 0px solid #fff;
+}
+#sender_acl_disabled {
+  display:none;
+  margin-top:10px;
 }