If a node is moved out of node-red core to an npm installable
package, the first time NR runs after the move it correctly
deletes the node-red version from the registry. However it was
also removing the node constructors registered by the new
npm installed version as it wasn't checking what it was removing
came from the now-removed node.
Splits registry up into smaller components.
Unit tests still drive api via registry/index_spec - still
need to split them up into the currently blank _spec files
