Allow hooks to be dynamically initiated based on entire namespaces

This is phase 2 of "dynamic hooks". The goal here is, if a namespace is full of repeating structures like this:

```
network.eth0.address
network.eth0.netmask
network.eth1.address
network.eth2.netmask
...
```

then sysadmin should support launching a dynamic number of hooks based on parts of that structure, like each of the nested interfaces.