Add translator to WAL replay tool
Add translator to WAL replay tool

This adds a new option flag `-x --names-translator`. If it points to a
json file, it will translate all keys (ignore case) with the values when
printing attributes.

E.g.:
    -x names.json

```
cat names.json
{
    "0xb4f44cd22a84DE0774B802e422D4c26A73Dd68d7": "initiator",
    "0x7f9902e21747AC5DABbd9Ba50E96F3b1f58Ae639": "mediator",
    "0x4B2F10eC7edc602915CE7db3547fc3352B09401C": "target",
    "0x0Ea30825657A15a8460bc025AA0608AB3405d585": "RTT"
}
```
will lead to output like this:
```
> ActionChangeNodeNetworkState
	node_address='[initiator]'
	network_state='reachable'
```

Furthermore, it allows to use the names for the `-n` and `-p` switches:
```
replay_wal.py -x names.json -p mediator -n RTT db-file
```

hackaugusto/raiden,hackaugusto/raiden