[OPENENGSB-3323] added a constant for the adding of the version of a model type
[OPENENGSB-3385] extended the EDBCommit with a revision number and a parent revision number
[OPENENGSB-3385] adapted the EngineeringDatabaseService to support the revision numbers
[OPENENGSB-3416] remove unused api-reference
[OPENENGSB-3442] extended EDBObject with staging id
[OPENENGSB-3442] comments
[OPENENGSB-3443] EDBStage
[OPENENGSB-3443] changed EDBStage
[OPENENGSB-3443] added EDBStage object to EDBCommit
[OPENENGSB-3443] added setter to EDBStage
[OPENENGSB-3443] set EDBStage to EDBCommit + new getObjects in EDBService