Remove unneeded columns from protocol table in esf and add status column

The protocol table contained columns for login-name, name, studypath, matrikel
of the student, but this data was not actually depending on the protocol, the
columns simply showed the global values of the student.
In contrast, the current status of the exam (registered, earmarked) was not
displayed, so added a cloumn for this.
Additionally the code was restructured and modernized.
Create JPA entity ArchivedProtocol and manager to archive old exam protocols

This new entity will be display in the user's esf and can be used to display
exam results wihtout the need to have a relation to any exam or protocol entity.
The mapping is done by the user's student number.
Currently there is no way to import/export or manually add/edit these protocols.
Update the esf student and edit controller to show archived protocols

To compensate for the additional usage of vertical space, we trim down the header
showing the personal information of the student by showing two colums and floating
the edit button and we reduce the number of rows in the tables.
Additionally fix some problems in the controllers and clean up code.
Delete obsolete hbm mapping and fix some annotation issues

Named queries did not have globally unique names.
Use hilo generator strategy for generating persistence keys.
Create xml export/import interface for archived exams

The xml export is based on XStream and JPA, which is why the performance especially
on writing is not very good.
We could use hibernate specific constructs to avoid loading all objects into memory
and write the xml directly into the output stream of the temporary file.
Create admin controller to export and import archived protocols

This controller uses the export/import interface that was introduced in the last
commit.
Include export/import controller into the admin panel and clean up code
Show closed-status of exams in protocol tables, fixes #44