Make Series Endpoint Accept Metadata Fields

[lkiesow]

This patch adds metadata fields to the REST endpoint for creating
series, making it far easier to handle. The old parameters are
unmodified and will take precedence to not break any existing
integrations.

This also fixes the bug that series may have been created with only half
of their data if parsing the ACL failed since the Dublin Core metadata
would have already been persisted at that point.

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