v0.5.6

• Expose request id to parent Rack application when using ApplicationInsights::Rack::TrackRequest middleware through env['ApplicationInsights.request.id'].
• Implement operation context functionality for ApplicationInsights::Rack::TrackRequest.
• Add functionality to accept a Request-Id header for telemetry correlation.
• Add operation context to request tracking middleware.

Version 0.5.5

• Add some basic logging when failed to send telemetry to the server
• Add timestamp as an optional parameter to the TelemetryChannel::write() method