optionally use source/target id's instead of names when building edges

If you build an edge between two nodes in the map topology editor, then rename one of the nodes it causes the links built between the nodes to disappear.

Example:

```
"edges": [
{
"capacity": "100G",
"source": "Node1",
"target": "Node2"
},
```

If I were to change "Node1" to "Node 1" then this link goes away. It would be nice if I could use "source-id": "08a6bfc0-0f80-45af-92fc-7e06c2fa59ae" instead so the link can follow the node rename.