Issue2620-RocksDB log path configurable: conf

Changed default value of commented dbStorage_rocksDB_logPath=
setting to blank value in order to match default behavior.

Author: dinghram

conf/bk_server.conf

@@ -706,7 +706,7 @@ ledgerDirectories=/tmp/bk-data
 # dbStorage_rocksDB_numLevels=-1
 # dbStorage_rocksDB_numFilesInLevel0=4
 # dbStorage_rocksDB_maxSizeInLevel1MB=256
-# dbStorage_rocksDB_logPath=/logPath
+# dbStorage_rocksDB_logPath=
 
 
 ############################################## Metadata Services ##############################################