node: Build hangs if `download` feature is enabled

[tcharding]

Something is wrong with the build lately but I've no clue what. It may be being obfuscated (or caused) by unrelated network issues I'm experiencing with my network.

[tcharding]

My hunch is it is to do with --all-features and chanegs in node v0.7.0 to how features are handled.

I manually updated the lockfiles for #146 using cargo check

[storopoli]

I've seen flaky downloads from https://bitcoincore.org/bin/ URLs in my corepc-node builds

[tcharding]

Oh is that right, good to know. Thanks man. That might also explain the flakey CI jobs I've been seeing lately.

[tcharding]

Perhaps we should cache the Core binaries so we don't download them ever CI run.

[tcharding]

#193 is a quick bandaid for local dev.