Crash on getDefinedFonts
## About this issue

- I see crashes for people using Android 5, mostly Samsung devices, when calling `init` method.
- Here is the complete crash log:
```
Caused by java.lang.ArrayIndexOutOfBoundsException: length=0; index=5475
       at java.lang.reflect.ArtField.getNameNative(ArtField.java)
       at java.lang.reflect.ArtField.getName(ArtField.java:91)
       at java.lang.reflect.Field.getName(Field.java:122)
       at com.mikepenz.iconics.utils.GenericsUtil.getDefinedFonts(SourceFile:55)
       at com.mikepenz.iconics.utils.GenericsUtil.getFields(SourceFile:23)
       at com.mikepenz.iconics.Iconics.init(SourceFile:54)
       ...
       at android.app.Instrumentation.callApplicationOnCreate(Instrumentation.java:1018)
       at android.app.ActivityThread.handleBindApplication(ActivityThread.java:4934)
       at android.app.ActivityThread.access$1600(ActivityThread.java:168)
       at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1454)
       at android.os.Handler.dispatchMessage(Handler.java:102)
       at android.os.Looper.loop(Looper.java:135)
       at android.app.ActivityThread.main(ActivityThread.java:5753)
       at java.lang.reflect.Method.invoke(Method.java)
       at java.lang.reflect.Method.invoke(Method.java:372)
       at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1405)
       at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1200)
```

## Details
- [3.0.2] Used library version
- [27.0.2] Used support library version
- [27.0.3] Used gradle build tools version
- [3.0.1] Used Android Studio version

Any idea what might be causing this?
