fix enrollment tab beans silently refreshed from DataTable.filter()

[rkrenn]

updates initiate from within enrollement tabs, such adding an enrollment status use primeface's clientside PrimeFaces.widget.DataTable.prototype.filter().

this in turn will silently cause to re-select the current row (subject list entry), which re-inits all the enrollment tab beans, effectively re-setting them. this also caused an issue observed in particular: deleting fails (with no error) after an intermediate enrollment status creation.

re-selecting the current row is now prevented by doing unselectAllRows() beforehand.