Added LoggerRequestId interface

Logger should implement this interface to support RequestID handling
Implemented LoggerRequestId interface in syslog-logger
Implemented RequestID handling

When request comes to FastcgiDaemon2 it tries to read REQUEST_ID Fastcgi
parameter. If parameter preset and current logger supports
LoggerRequestId interface FastcgiDaemon2 sets value of this parameter as
a RequestID for current request.
Merge branch 'idents'
Version up to 2.10-24