Audit trailing

*Title: Audit trailing

*Incentive:
At big sites with many admins / users / editors you need a better logging.

*Documentation:
The possibility to audit some things like user name, time or IP address etc 
when removing content, assigning sections etc.

The new settings have been added:

- audit.ini[AuditSettings].LogDir
  Where the log files should be placed.
- audit.ini[AuditSettings].Audit
  If 'enabled' the possibility will be enabled.
- audit.ini[AuditSettings].AuditFileNames[]
  Audit file names setting.
  The key of AuditFileNames[] is the name of audit and value is file name.
     For example:
     AuditFileNames[<name of audit>]=<file name>

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For example:

# Failed login attempts will be logged
AuditFileNames[user-failed-login]=failed_login.log
(If audit of failed login is not needed just comment or remove this line.)

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Always clients IP address, time and user name will be logged.
Things which can be logged:
- failed login attempts 
- user IP address
- who deletes which content (node id / object id / content name)
- who moves content (node id / old parent / new parent / object name)
- who changes which role(s) (role id / role name)
- who assigns which role to whom (role id / role name)
- who assigns which section at which node (section id / section name)
- who deleted which order in shop (user / order id)

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*Usage

If you want to use another audit you should:
1. Add audit name as KEY and log file name as VALUE to audit.ini[AuditSettings].AuditFileNames[].
   (e.g. AuditFileNames[user-login]=login.log)
2. Set audit.ini[AuditSettings].Audit to 'enabled'
3. Use php code like:

       include_once( "kernel/classes/ezaudit.php" );
       eZAudit::writeAudit( 'user-login', array( 'User id' => <userID>, 
                                                 'User login' => <userLogin>, 
                                                 'Name of something' => <valueOfSomething> ) );