AWS DynamoDB, Lambda, SQS and SNS plugins, webpack

[tom-pytel]

The main things here are 4 new AWS SDK2 plugins and webpack support. The full list is:

• AWS SDK2 DynamoDB plugin.
• AWS SDK2 Lambda plugin.
• AWS SDK2 SQS plugin.
• AWS SDK2 SNS plugin.
• Instrument deprecated but possibly still used exit calls done(), succeed() and fail() from AWS Lambda function.
• Allow passing trace ID in AWS Lambda function parameters to allow linking outgoing to incoming calls.
• Extend AWS flush from boolean always/never to time threshold.
• Made agent.flush() wait on any unfinished Spans before waiting for protocol send to make sure all Spans in progress finish.
• Webpack support, can now run with most plugins from a bundle where before agent did not work at all from a bundle.
• Changed builtin plugin "detection" to explicit specification by plugin.
• Fix sequential invocation of Lambda function which does not flush and leaves an async component waiting to complete a Span incorrectly linking to a previous sibling Span.
• Fix double logging and undefined version print if plugin not supported.
• Fix Axios plugin to not return error but rather empty not supported version string if not supported (is deprecated anyway due to not compatible with Axios v1.0+, need to update).

The AWS plugins are in the plugins/ directory and not the aws/ directory because they are normal Node plugins which can be used on or off AWS to access those AWS services.

[tom-pytel]

Good to go.