re: #159 - sort out content namespace

* registering namespace with http://www.mediawiki.org/wiki/Extension_default_namespaces

Change-Id: I990f2e67875b12ad9c455e78ca870e3231c89e47
Merge branch 'assembla/159'

Change-Id: I79ec864afedb8a8dfe59d5a87d709de4d8f0b02a