GCSFuse code change to write the logs to syslog files

[raj-prince]

Description

1. Reverts Revert "GCSFuse code change to write the logs to syslog files" #977
2. Modified log behavior - If user passes --log-file in case all the logs will be written to given log file. Otherwise in background mode gcsfuse will write the log to syslog and in foreground mode logs will be printed to console as stdout/err.

Testing

1. Manual - Checked all the four behaviors manually.
2. Integration Test - NA
3. Unit Test - NA