Ensure Windows builds work
The Windows tests aren't completing for Travis due to: https://github.com/near/near-sdk-as/issues/23
When that's ready, let's fix the Travis yaml to stop on errors that Windows finds during CI tests.
As I'm working locally to install everything and get setup on windows, I found that asdf, isn't windows compatible. However, I just used https://github.com/coreybutler/nvm-windows and it worked like a charm.
We also need to note we require node > v12
Note that logic can be borrowed from here: https://github.com/near-examples/token-contract-as/pull/10
Partially addressed by #142