Migrate module to require Go 1.20 as a minimum

Merge pull request #2 from rgee0/bumpv2

Append v2 to module path

Add SHA256 support

Update README.md

Update README.md

Add Go module

Create LICENSE

Update README.md

Update Validate to expect "sha1=" prefix for hash method. Other

Add "Sign" function

Add tests for empty hub-signature

Update README.md

Update comment + ns

first commit