replace klog with zap log.

[morvencao]

ref: https://issues.redhat.com/browse/ACM-17785

This PR replaces klog with zap logger. The log levels are:

• DebugLevel: Detailed debugging.
• InfoLevel: General info.
• WarnLevel: Warnings.
• ErrorLevel: Errors that don’t stop the program.
• DPanicLevel: Serious issues causing a panic when synced.
• PanicLevel: Immediate panic.
• FatalLevel: Critical errors that stop the app.

It also allows changing the log level at runtime via a ConfigMap in the maestro namespace:

# oc -n maestro get cm maestro-logging-config -o yaml
apiVersion: v1
data:
  config.yaml: |
    log_level: debug
kind: ConfigMap
metadata:
  name: maestro-logging-config
  namespace: maestro

This allows changing the log level without restarting the maestro pod.

[morvencao]

/assign @clyang82