DICOM: expand sequence reading to include known sequences (rebased onto develop)



This is the same as gh-1062 but rebased onto develop.

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See QA 9184.  With this PR, more original metadata entries should be present, including multiple entries for tag (0008, 0104).  See also http://lists.openmicroscopy.org.uk/pipermail/ome-users/2014-April/004336.html.