Confusing loading state in Battery Saver

Dear developer,

I noticed that when I enable Battery Saver on Android 8.1, the indeterminate `ProgressBar`s in the app are not properly shown. This is a known problem in Android API level <28, see e.g. [this StackOverflow question](https://stackoverflow.com/questions/35221706/progressbar-disappears-in-battery-saver-mode-android-5-x). Battery Saver disables animations, also on progress bars on these versions. This is quite confusing because the loading state is not properly represented. It is fixed in later Android versions, where progress bars do appear and animate.

Looking at the code, indeterminate progress bars are created here:

```
className='de.luhmer.owncloudnewsreader.PodcastFragment', lineNumber=473
className='de.luhmer.owncloudnewsreader.adapter.NewsListRecyclerAdapter', lineNumber=229
```

To fix this issue, one can check [ValueAnimator.areAnimatorsEnabled()](https://developer.android.com/reference/android/animation/ValueAnimator) and provide a different UI element, such as a text label, when animations are disabled.