Encoding/decoding negative integers and bigger integers

[killerstorm]

I added support for encoding & decoding negative integers. Existing implementation was producing erroneous values.

I've added tests for numbers at the edges: -1, -128, -129. No extensive testing was done.

[indutny]

I actually just added eslint to the package.json. So you can run npm run lint to fix the most of these issues.

[killerstorm]

Thx, I also want to fix encoding JS integers > 2^32-1 while we are here. If you don't mind I'll redirect them to BN.

[killerstorm]

Hi, I fixed lint issues and also added support for integers >= 2^31.

I don't see BN.fromTwos in BN library so I don't see an opportunity to handle it in a more efficient way.

Note that test "should encode OCSP request" fails, but it fails without my changes too.

[blmalone]

Is this going to be merged?

[Kalmac]

Is this only a conflict issue ? I need number support > 32 bits.