Fix deprecated args validation
Fixes check for deprecated arguments to cater for key=value arguments. It also logs the warning if a deprecated flag is used.
Relates to #260 (closed)
The warning message will look like
WARN[0000] Using deprecated arguments error="Deprecation message: -auth-client-id, -auth-client-secret, -auth-secret should not be passed as a command line arguments"
Edited by Jaime Martinez