Add django-extensions

django-extensions has excelent shell_plus, with integrated ipython and
preloaded modules.
News index and news details

Finally news index and news details are fully implemented!
Homepage app

Now I created this app just to show all news items in index page.

Previously NewsIndex was set as site.root_page, but then Wagtail eat
`/naujienos` prefix from all pages that are descendants of NewsIndex.

Now NewsIndex is descendant of IndexPage and `/naujienos` prefix is back.
Fix index and news links