fix image cannot be deleted
remove 'data-drag-source' attribute on 'dragend'
build
Merge pull request #60 from corespring/fix-disapearing-nodes-on-drop

Fix disapearing nodes on drop
fix image tests
Merge branch 'master' into mini-wiggi

* master:
  fix image tests
  build
  remove 'data-drag-source' attribute on 'dragend'
  fix image cannot be deleted