DublinCore import/export roundtripping fixes

Fixes #4302. Squashed commit of the following:

commit 4355e53653fd2529dc4c686528284848033f75d4
Author: José Raddaoui Marín <raddaouimarin@gmail.com>
Date:   Sun Jan 20 07:03:54 2013 +0100

    Add language case for DC languages

commit b0ae02015b4cbe05d4ab97c29e3398b4053870a3
Author: José Raddaoui Marín <raddaouimarin@gmail.com>
Date:   Sun Jan 20 07:01:23 2013 +0100

    Change how the elements are taking in DC

    Replace XPath query by getElementsByTagName and modify dc.yml,
    where the Xpath condition is replaced by the tag name.