Update cosmwasm 0.4.1

[ethanfrey]

Closes #8 once both osx and linux dlls are in

Use the newest of the new...

• singlepass backend compiler
• gas metering enabled and working
• new json and error libs, contract size+gas 40% of previous
• general cleanup

[ethanfrey]

@shanev this is the big update process...

can you try make build-rust and then make test on osx?
if you have any test failures due to gas metering, please let me know.
otherwise just commit the *.dylib output and we are good.

Oh, you need nightly rust now :sigh: for the gas metering compiler.

rustup toolchain install nightly
rustup default nightly
rustup target add wasm32-unknown-unknown
# yes this last one again, you have it for stable, but need to run again for nightly

[shanev]

No failures with rust nightly. Checked in the macOS lib.

[ethanfrey]

Awesome. Thanks!