Correct output escaping in metabox

Fixes #4
8 jobs for add/1-bulk-action in 3 minutes and 22 seconds (queued for 3 seconds)
Status Job ID Name Coverage
  Test
passed #3791
PHPCS

00:01:36

passed #3785
PHPunit:PHP5.3:MySQL

00:02:43

passed #3786
PHPunit:PHP5.6:MySQL

00:02:46

passed #3787
PHPunit:PHP7.0:MySQL

00:02:38

passed #3788
PHPunit:PHP7.1:MySQL

00:02:28

passed #3789
PHPunit:PHP7.2:MySQL

00:02:39

passed #3790
PHPunit:PHP7.3:MySQL

00:02:36

 
  Deploy
passed #3792
PluginSVN

00:00:34