Updates specs to use new rails5 format.
The old format:
`get :show, { some: params }, { some: headers }`
The new format:
`get :show, params: { some: params }, headers: { some: headers }`
The Correlation ID is taken or generated from received X-Request-ID.
Then it is being passed to all executed services (sidekiq workers
or gitaly calls).
The Correlation ID is logged in all structured logs as `correlation_id`.
