Make SchemaInfo upgrade work on SQLite

I just upgraded to your fork and found two bugs that prevent it from working on SQLite with older databases. 

1) Older SchemaInfo had only Version column so not only Scope but also TimeStamp column should be created during upgrade

2)  RemoveAllConstraints/GetConstraints inherited from base class doesn't work -> I choose to return empty array (e.g. ConstraintExist does the same - probably because it's not easy to retrive get them from SQLite)