Enhancement: express all units in wei

Given that the parameters logged to stdout, and the parameters passed to flags in `go-livepeer` are expressed in wei, it would help to keep that consistent in this tool.

e.g. I get this from the O stdout:
```
Cached gas price: 1000000000
```
which is expressed in `wei`

and I am asked for this in this calculator:
```
Enter the gas price (gwei) to use for ticket redemption transactions:
```

Start by locating the calculator entry point that prints the gas-price prompt and accepts its value. Review how the value is described and used for ticket redemption transactions; done means the calculator consistently expresses and accepts gas prices in wei, matching the logged and go-live parameters.

Written by the indexing model from the issue text.