Update documentation and remove use of deprecated method

Change-Id: I61665642f8b33118b217de6e7da9866d2166da85
Use WikiPage::factory() instead of Article::newFromTitle()

Also change way of getting context, and add a fixme for an undefined variable.

Change-Id: Ic5891c2cd71a2bca5bb2e703aae443f875c0063a