Fixes #19895 - Fix Style/RedundantReturn cop

Fixes #22493 - structured logging support

Refs #18675 - Optionally load prometheus exporter

In case the bundler group telemetry is not installed, we should handle
that.

This moves the middleware loading to better match the other middleware.

Fixes #22613 - Drop Rails <5.1 ParseError

Fixes #21991 - add Rails 5.1 ParseError exception

fixes #10982 - configure RestClient log to 'proxy' logger

Request/response information is sent to the proxy logger, showing the
URLs called, headers, request body etc.

The X-Request-ID header is now also set in the proxy requests to a
random ID stored in the session, to prevent the user's real session ID...

Fixes #16491 - Upgrade rubocop to version 0.42

fixes #15863 - add short session or request ID to logs

New middleware stores the session and request IDs (either from
X-Request-ID or a UUID generated by Rails) in the logger's thread
storage. The truncated session ID is now logged by default to minimise...

Fixes #7230, #12021 - Upgrade to Rails 4.1.5

This commits upgrades Rails to Rails 4.1.5. See a description of the
changes included here, and go to the pull request in GitHub to see more
detailed explanations:

• Update gems to a Rails 4 compatible version, including dependencies...

fixes #6774 - in case of parsing of non json or broken json, return 400