Streamline Logging to be more useful for using the proto-kms

This aims at addressing issue #3 (closed)

Problem Description

Right now logging is happening in quite an unstructured way across multiple places, e.g.,

• not log-levels are being used
• the originating code part is not visible, except it is manually added to the log-message

Applied Changes

• move from go's log pkg to sirupsen/logrus
• add log-levels
• loglevel to be handed over during start of the pkg separately for the quantlum-layer and the proto-kms (using logrus instances)
• log.SetOutput(os.Stdout) to be set during boot, if log messages should not go to stdout
• log.SetFormatter() to be added
• use of log.SetReportCaller(true) to add origin code of the message to log-message in Trace level