Digital object fixes in EAD export, fixes #2589
Control area import fixes in EAD, fixes #2668

Squashed commit of the following:

commit 1442111061f46794ab2e1dec59ed1ed1199b481f
Author: José Raddaoui Marín <raddaouimarin@gmail.com>
Date:   Tue Apr 9 04:37:42 2013 +0200

    Remove duplication of sources on EAD import

commit 85d15b01e0f6b78e383692e075c6a9785fd8571e
Author: José Raddaoui Marín <raddaouimarin@gmail.com>
Date:   Tue Apr 9 04:02:20 2013 +0200

    Change attribute name for status in EAD

commit 5d3bfeea2eea8b703525e5fb42e9544b7ef73608
Author: José Raddaoui Marín <raddaouimarin@gmail.com>
Date:   Tue Apr 9 04:00:10 2013 +0200

    Add archivist notes EAD import
Populate appraisal field

Populate the appraisal field in the information object from
the accession form. Fixes #3961.
Change event type export in EAD, fixes #4418