Now log file name is unchanged : current log is still /log/error.log \o/
Rotation check (using file last modification time) is done :
* on each file write : we don't want to miss calls if session last from 23:59:59 to 00:01 for example ! Though the filemtime() call is done once per session to lower performance impacts
* using a new background process (LogFileRotationProcess)
File renaming on setup is therefore removed.
Also the interface is renamed (from ILogFileNameBuilder to iLogFileNameBuilder) to conform to iTop convention.
