Add v2 to module import path

Add v2 to module import path per module release workflow

References:

• https://go.dev/doc/modules/release-workflow#breaking
• https://go.dev/doc/modules/version-numbers
• https://go.dev/blog/versioning-proposal

Upgrade X-Ray client to AWS SDK for Go V2

This is a breaking change to the package interface, so it requires a major version bump.

Housekeeping release

• Tweaks to documentation
• Tweaks to configuration of continuous integration by Travis
• Minor Go module/build changes

Initial stable release

Initial stable release