Expose list of known addresses in repl

I would like to do this:

```
eth address:add --network 4 dai 0x5592ec0cfb4dbc12d3ab100b257153436a1f0fea
eth repl --rinkeby
> addresses.dai
"0x5592ec0cfb4dbc12d3ab100b257153436a1f0fea"
```

Shouldn't be that hard. Just getting the addresses from the conf and then using only the ones for the current network (or the ones with network `*`).