Use the id field of person fields e.g. authors, editors etc
Add parent and parentauthors when inserting modules

If module B is derived from module A, in the epub, we should get a
"derived_from_uri" field which looks something like
http://cnx.org/contents/module_a_uuid@version
The ident hash of module A is extracted from the "derived_from_uri" and
is matched against the existing modules to get the module_ident and
authors fields.  The module_ident and authors are then used as the
"parent" and "parentauthors" fields in the module B.
Remove duplicate call to add_pending_resource
Merge pull request #9 from Connexions/update-person-fields

Use the id field of person fields e.g. authors, editors etc
Merge pull request #10 from Connexions/derived-copies

Add parent and parentauthors when inserting modules
Use the person struct for all attributed roles values.
Adds license acceptance routes.
Add all roles to the license acceptance list.
Change the publication state to 'Waiting for acceptance'.
Adds role acceptance routes.
Adjusts publication state checking, this breaks the publication trust scenario.
Adjusts state checking to first check the document's state before diving into the aggregate state.
Allows for missing role fields, which is valid for some of the fields.