support BCDB as an optional explorer backend

[GlenDC]

For now this will be done implemented as a patch version of stdnet/testnet, so we can ship ASAP. When we feel ready for it we can refactor, clean up and get up to date with Rivine, but for now this needs to be shipped immediately.

Feature request for: https://github.com/threefoldtech/jumpscaleX_libs/issues/4 (deadline: NOW)

Details to follow.

[robvanmieghem]

@GlenDC why is this still in state blocked? Issue threefoldtecharchive/jumpscaleX_threebot#85 which was mentioned in https://github.com/threefoldtech/jumpscaleX_libs/issues/4 was resolved 20 days ago.

[GlenDC]

Is no longer blocked, just was never untagged as there has been no progress on this.