Mediapackage metadata unable to contain multiple elements with the same 'name'

[andiempettJISC]

currently if you generate the mediapackage episode.xml from opencast with galicaster and it has multiple elements with the same name, only one will be used:

example episode.xml from opencast:

<dublincore><dcterms:isPartOf>example</dcterms:isPartOf><dcterms:temporal xsi:type="dcterms:Period">start=2017-02-06T09:00:00Z; end=2017-02-06T09:55:00Z; scheme=W3C-DTF;</dcterms:temporal><dcterms:audience>restricted</dcterms:audience><dcterms:audience>enrolled</dcterms:audience><dcterms:title>example - 06-Feb</dcterms:title><dcterms:available xsi:type="dcterms:Period">start=2017-02-07T10:00Z; scheme=W3C-DTF;</dcterms:available><dcterms:created xsi:type="dcterms:W3CDTF">2017-02-06T09:00:00Z</dcterms:created><dcterms:source>example</dcterms:source><dcterms:spatial>example</dcterms:spatial><dcterms:identifier>example</dcterms:identifier></dublincore>

galicaster when processing the xml will only write out one 'audience' element in the above case.

i've traced the issue to:
line 1438 marshalDublincore https://github.com/teltek/Galicaster/blob/2.0.x/galicaster/mediapackage/mediapackage.py
this method processes the xml DOM and puts all the metadata into a dict by 'name' self.metadata_episode[name]. so if the 'name' is the same then it gets overwritten.
also
line 59 _checknget https://github.com/teltek/Galicaster/blob/2.0.x/galicaster/mediapackage/utils.py
this along with _checkget look up the element by name but always use [0]. if multiple elements with assigned to the named tag then you'd need to look beyond the zeroth element: _checkget(archive.getElementsByTagName(name)[???])

so i've quickly hacked this to work on our current 1.3.x install, but this isn't pull request worthy.
Instead i'd suggest that the metadata handling is re written to be a bit more flexable, it should 1:1 represent the mediapackage xml sent to it from opencast

[andiempettJISC]

so heres the commit, just to reiterate, its not very good! but worth a look at to understand the issue
UoM-Podcast@b4b0752

[JamesUoM]

I brought this up at the Opencast conference, and have requested that the XML handling be rewritten. I've created as separate issue that discusses the wider issues.

#470