This commit adds the option (enabled via environment variable) to the
logging middleware to log real/originating IP address of a client based
on specific headers.
Three headers are supported: True-Client-IP, X-Real-IP, X-Forwarded-For.
This is particularly useful when there is proxy server(s) sitting
between step-ca and client.
Implements #1995
Adds `STEP_LOGGER_ONLY_TRACE_HEALTH_ENDPOINT` environment variable to
opt-in to only logging successful /health requests at the Trace level
Fixes#420
Signed-off-by: Dominic Evans <dominic.evans@uk.ibm.com>
