Enables WP custom field localization in factory
Adds CF localization spec for work package index
Adds CF localization spec for project settings
Adds spec for lang tags on CF new page
Returns the custom field's localization
Sets the 'lang' attribute for custom field content
Changes lang tag according to user selection
Shows lang tag for custom fields on WP show
Localizes CF name on project settings page
Adds changelog entry
Merge pull request #812 from opf/fix/accessibility_label_document_language_custom_fields_2244

[FIX] Accessibility label document language custom fields 2244