v2.0.0

⚠ BREAKING CHANGES

• middleware: We now promote the logEntry metadata field in a
  winston log info object to be the logName reported to Stackdriver. This means
  that the logs will show up under the log name specified by the logName. In addition
  there are several breaking changes to users of the express middleware:

• The middleware function has been replaced by makeMiddleware.

• makeMiddleware expects a winston logger to be passed in.

• Previously, we would append a _applog suffix to the user provided
  application log name. We no longer do that. We use the user provided
  log name for the application logs. The request logs now have a suffix.

Rationale:
Let the middleware users provide a winston logger that we annotate with a transport
rather than creating two winston loggers on user's behalf. We avoid the
need for having two transports by pomoting the logName field from the
winston metadata into the LogEntry. This allows a child logger to write
to a different stackdriver log stream - as needed for request bundling.

Bug Fixes

• deps: update dependency google-auth-library to v5 (#375) (f0ec607)
• docs: generate correct examples in README.md (#376) (7517462)
• middleware: allow users to provide middleware (#369) (e61dad9)
• middleware: use winston provided child logger api (#359) (5d83565)

Features

• middleware: make API more ergonomic (#364) (5ecdeb4)