Adding ghost relations.

Relations are now added to changeset.
Responding to reviews

* Move ecs flag to mv
* Do not modify changeset in place
* Add comments
Tests updated to reflect new _buildHierarchy behavior.
Make prep
Comments added around JSON.stringify
Merge pull request #253 from makyo/relation-ecs

Relations are now added to changeset.

To QA: use flags ecs and mv

* Drag mysql and wordpress onto the canvas.
* click deploy once for each
* long-click and add a relation between the two - the relation line will disappear
*  Ensure that the relation is in the changeset by investigating app.ecs.changeSet in the javascript console.
* Run app.ecs.commit(), ensure that the relation is in the database.