Dynamically add new tables to existing databases

[FlorianK13]

If new tables are introduced by BNetzA, the current code cannot simply add them to an existing database. For example, when running db.download() and there is already a database initialized, a new table will cause an error. This should be changed, ie. new tables should be added automatically.

They should take the name from orm.py if the new table is already part of a new open-mastr release. Or they should just use the german name otherwise.