fix: bignum parsed as Value

[ahmedcharles]

Fixes: #31

[ahmedcharles]

I added a test which verifies that bignums now get represented by the shorted byte string (without leading zeros).

[ahmedcharles]

Thanks.

[rjzak]

Thank you for your recent PRs, they're a big help to the project. If you're not planning anything soon, maybe I should do a release.

[ahmedcharles]

I just filed #116. I would like to resolve #36 but that will likely require significant changes to the api and I'm thinking about what the best approach there would be. I'll follow up in that issue.

That said, doing a release after that last PR seems like a good idea. Thanks.