Google Cardboard now runnable in fragment

I’ve updated the jme-cardboard project to support fragments now as well. The old CardboardHarness still works, but eventually it will be phased out in favor of CardboardHarnessFragment.
Instructions on how to use it are on the project site.
There’s currently an issue with the latest cardboard version 0.5.4. I hope to solve it soon, but use 0.5.3 in the meantime.