IMPLEMENTED:  API is able to delete values of sessiondata
IMPLEMENTED:  API is able to delete values of sessiondata

API is able to delete all values of sessiondata and the paramater all
deletes also sessiondata

AMOSus/amos-ss16-proj6,AMOSus/amos-ss16-proj6,AMOSus/amos-ss16-proj6,AMOSus/amos-ss16-proj6