Changed the article system

While preparing the upgrade to WoltLab Suite 3.1 I changed from WoltLab Suite Blog to the built-in article system of WoltLab Suite Core. Since I »importored« everything manually there may be some bugs. Should you stumble upon one, please give me a hint. The design is still "out of the box so it seems a bit strange but this will change soon.

The change also meant that the name »Journal« won't be used anymore. It didn't fit anymore either. Like before you'll still find articles on updates and releases, tutorials, announcements and every now and then some articles on diverse topics. The nerdy users already found the category »Apple« - this will be filled with content asap.

If WoltLab won't include breaking changes while still in beta and all apps I need to use will receive updates in time, then it would be possible that Elevenfour upgrades quickly this time.