Univention Corporate Server 4.0 erratum 65 (bugfix)

This update addresses the following issues:
* Added support for the following operators in a UDM filter: <, >, <=, >=.
* Changing the attribute DNS time to live from an empty value does
  not trigger an error anymore.
* It is now possible to change the password of a user after setting
  an empty password length in the referenced password policy.
* Set a default value for the property "CtxRASDialin".
* A PNG file can now be specified as user photo. It will be internally
  converted into JPEG.
* Exceptions during the creation of UDM objects are now handled.