styling: setting size on mention gravatars

rhodecode/public/css/codemirror.less

@@ -379,6 +379,8 b' span.CodeMirror-selectedtext { backgroun'
 }
 
 .CodeMirror-hint-entry .gravatar {
+  height: @gravatar-size;
+  width: @gravatar-size;
   margin-right: 4px;
 }