Fixes Issue #108 Tabris UI not compatibel with JFace Databinding

The TabrisUI has implemented the EntryPoint Interface. This was splited
into two classes, TabrisUI and TabrisUIEntryPoint. When using JFace
Databinding a developer can now implement his own EntryPoint and
creating the TabrisUI by himself.
Merge "Fixes Issue #108 Tabris UI not compatibel with JFace Databinding"