ChangeJson: Don't use ChangesCollection

This change removes circular dependency:

  ChangeJson depends on ChangesCollection
  ChangesCollection depends on CreateChange
  CreateChange depends on ChangeJson

by not using ChangesCollection in ChangeJson class.
This is needed to remove the needs to use factory to inject
CreateChange in ChangesCollection. This is needed to move
ChangesCollection and ChangeJson to singleton scope. This is
done in the follow-up change.

Change-Id: I2fc4ac3d7f00e91e934fd496c164555ab751babc
1 file changed