route namespace

design notes for #850

I estimate completing the implementation will take half a day.


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UPDATE (from Adam): This took over a day to change it from design to implementation, including hours of pairing, but the estimate was for Jean-Paul alone and I'm slower. There are also a few TODOs with questions about how to continue.

Fixes #850 

It is tests like this which prompted having a `namespace` attribute on `MemoryNetwork`. Either the default string has to be duplicated or the whole proxy cannot be compared.

In this file now are examples of both. This test tests only the `ip` and `port` of the expected proxy while `test_proxy_needs_creating` above duplicates the (poorly named) ``"a_namespace"`` default. I wanted to work around duplicating the strings, but tests like the one above would get so messy or lose much of what they're testing.