fixed: issue with stripped tags on template save
fixed: resending of transactional mails
fixed: registration not stored if username was missing
fixed: bounce test failed on some servers
added: additional security steps on form submission
added: option to recheck for updates on the dashboard
* fixed: editbar position issue on Chrome 61
* fixed: background image not editable if its the first of the template
* improved: placeholder image handling
* improved: loading of user met values
* removed: deprecated jQuery methods
improved: translation checks and loading
improved: loading of translations
fixed: assigned unchecked lists on form submission if user choice is enabled
fixed: PHP warning on bounce handler
added: remove_custom_value method to remove meta values of subscribers
added: Mailgun delivery option to setup
