Add update status values for DOI table
fix conflicts
Add delete option. Delete DOI on command line
Fix delete from DOIOrganiser
DOIIdentifierException use default message if no message is set.
Added method to extract DOI out of external format.
Add DOI in form of an operable URL to Item metadata.

We add DOIs as dc.identifier.uri like it is done with handles.
Unit test for DOIIdentifierProvider.
Typos.
Added DOI.RESOLVER instead of using "http://dx.doi.org" everywhere.