Change the XML namespaces on the mediapackages to be compatible with OC-MH 1.4

[rubenrua]

NOTE: Check if the XML namespaces brakes the backwards compability

The XML will be like:

<?xml version="1.0" encoding="utf-8"?>
<mediapackage xmlns="http://mediapackage.opencastproject.org" 
      duration="1995" id="f13e2862-3dc0-4da1-9e0a-4c79271f2735" start="2012-08-02T14:20:11">
  <media>
...

[rubenrua]

See OC-MH ticket http://opencast.jira.com/browse/MH-9256

[rubenrua]

See the branch https://github.com/teltek/Galicaster/tree/dev_xml_namespaces

[rubenrua]

OC-MH < 1.4 works with namespaces. Branch merged in master.

[hectorcanto]

Schedules: works on 1.2.2 from 1.2, 1.3 and 1.4
Ingest without using namespace to 1.2 & 1.3: OK
Ingest without using namespace to 1.4: fails, a erroneous MP appears

Ingest using namespace to 1.2 & 1.3:fails, a erronous MP appears
Ingest using namespace to 1.4: OK

Patched 1.4:
Works using namespace of not.

1.2.2 Galicaster local MP:
New ones will have namespace
Old ones will be updated once a operation (any) is performed.