show all button breaks

[willzeng]

Have identified two seperate issues:

• [x] Create a new node. Click Hide All. Click Show all. The newly created node does not appear. In short, newly created nodes are not loaded by show all. This is likely due to some bug from using the prefetch to flash load on showall when new nodes have not been added to the prefetch.
• [x] Create a new node X. Create a new connection between X and some existing node. Hide All. Show All. This breaks the d3 viz, probably because of a connection being loaded without the node being loaded due to above error.

[willzeng]

@davidfurlong Figured out how to replicate this.