Apply empty value of origin node to listeners on update.
Remove picture in the listener node when removed from origin.
Adding comment and fix minor bug.
Merge branch 'SCHOLAR-3.x' into 4373-empty-fields
Write test for verify empty people fields sync as expected.
Merge pull request #5301 from openscholar/4373-empty-fields-tests

Write test for verify empty people fields sync as expected.
Merge pull request #5295 from openscholar/4373-empty-fields

Apply empty value of origin node to listeners on update.