Reenable test builds

[cag]

(For Geth and OpenEthereum support)

[germartinez]

I see travis.yml includes tests against Ganache and Open Ethereum again using gunash 👍
I think Geth is missing, isn't it? https://github.com/cag/gunash/blob/main/index.js#L51
Should we also add Nethermind? https://github.com/cag/gunash/blob/main/index.js#L82

[cag]

I tried testing with Geth but now it's actually failing with the relayer, possibly because they now actually error in their own way on eth_call failures instead of succeeding with the revert data as the return data, though I'm not entirely sure.

As for Nethermind, I keep running into issues. Like there's this issue, which indeed did get solved, but also in the same release that that issue got solved, Nethermind locked down their dev accounts behind a password that can only be gotten from the stdout of the node process, and since Gunash relies on Docker, that stdout output has to be gotten via a separate process listening for the data on the Docker logs. Anyway, it's not impossible, but it is definitely a wrench.