Merge branch 'patch-2' into 'stable-3.1'

When uploading a logo which is smaller than the current ispconfig one, then the …

…logo will be on the left side of the header. In my opinion it will look better when it's centered.
You could vote about it ;)

See merge request !359

interface/web/themes/default/templates/main_login.tpl.htm

@@ -27,7 +27,7 @@
   <div class="row" style="margin: auto; width:100%;">
     	<div class="col-md-4 col-md-offset-4">
     		<div class="panel panel-default">
-			  	<div class="panel-heading" style="background: linear-gradient(to bottom, white, #eef0f2);">
+			  	<div class="panel-heading" style="background: linear-gradient(to bottom, white, #eef0f2);text-align:center;">
 					<img src="{tmpl_var name='base64_logo_txt'}">
 			 	</div>
 			  	<div class="panel-body">