PLT-2321 Move the toggle icon next to the link being previewed (#3071)

* PLT-2321 Move the toggle icon next to the link being previewed
only applicable to one-line messages started with link

* remove useless "Youtube" header when no title is available

* allow breaking long links instead of toggle

* simplify "/" to "/<wbr />" replacing
fix empty post without additional content body

* discard buggy "simplification"

webapp/sass/layout/_post.scss

@@ -914,9 +914,13 @@ body.ios {
         cursor: pointer;
         display: inline-block;
         font: normal normal normal 14px/1 FontAwesome;
-        margin: 5px 0 10px;
+        margin: 0 0 10px;
         text-rendering: auto;
 
+        &.pull-left{
+            margin: 5px 5px 0 0;
+        }
+
         &:hover {
             text-decoration: none;
         }