upgrading structure + dependencies

What's Changed

• improve generic apdu error code message to better point users to ledger issues by @felipemadero in #31
• upgrading deps by @jleni in #34
• refactoring + repo structure improvements by @jleni in #35
• update grpc by @jleni in #36
• Bump gopkg.in/yaml.v3 from 3.0.0-20200313102051-9f266ea9e77c to 3.0.0 by @dependabot in #30

New Contributors

• @dependabot made their first contribution in #30

Full Changelog: v0.14.3...v0.14.4