cleanup README and example config (#247)

* Indicate defaults for logging parameters
* Remove log_to_file from example config
* Remove online_delete from example config

example-config.json

@@ -31,12 +31,10 @@
     },
     "log_level":"debug",
     "log_to_console": true,
-    "log_to_file": true,
     "log_directory":"./clio_log",
     "log_rotation_size": 2048,
     "log_directory_max_size": 51200,
     "log_rotation_hour_interval": 12,
-    "online_delete":0,
     "extractor_threads":8,
     "read_only":false
 }