Fix schema passing when updating a dataset

There was a bug because the schema of the context being created was not
invoked. Hence, instead of the schema the function was passed leading to
malfunction.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>
Fix bug where deprecated dataset is revived

Due to a mishandling in the link checker deprecated datasets which have
been deleted were activated again. By adding a deprecated tag and
checking against it this case is now handled.

Signed-off-by: Konrad Reiche <konrad.reiche@gmail.com>