Revert to previous revision
Remove Roles from Users in many places.

Users aren't directly associated to users anymore.

This also removes some TODOs.
Make the deletion of groups configurable.

Give groups a field that controls whether they can be deleted.
Added transient getRoles() method to User model.

The roles of a user will be the (distinct) unification of all roles of all his
groups.
Database dao improvements

* Support queries using OR connected filteritems on subentities (Both in getTotal and getDataByFilter)
* Give hints when Introspection in getAllFields failed due to possibly not following the Java-Beans specification

TODO both getTotal and getDataByFilter are way to big and have copied code all over. They need to be refactored.
Add the NotIn operator.

Also refactored HibernateFilterItem class and implemented some missing operators.
Set the deletable flag to false when initializing groups.
Remove misleading comment
Add hashCode, equals: Avoid duplicates in HashSets
Logging imporved and smaller refactoring.
Exception message improved
Removed old/uncommented code.
Repaired failed build. Using apache-commons-lang3 now.
Smaller improvements & bugfixes for layer-deletion

  - Removed getMapLayers method from usermodel, can now be retrieved via
    layerservice
  - Client now only sends the id of the layer to be deleted
  - Added new methods to determine the layers of a user granted by groups
    or ownership
  - Fixed deletion of temporary-layers
User / Group Administration

  - Added new JSON-userserializer to display owner field as integer on MapLayers
  - Removed jsonignore from maplayer model on owner field to display
    the owner (user id)
User / Group Administration

  - Groups get now JSON-serialzed again over leanbasemodelserializer
  - Groups of maplayer are now fetched eagerly
Organize imports.
Give users a first- and lastname.
More user properties.
Added/enhanced toString() methods to/of all model classes.