Enable support for files that Fiji wants to ship

The Fiji repository on GitHub has these files in the `plugins` folder:

* plugins/Examples/Scala_Test.scala
* plugins/Examples/TrakEM2_Add_Balls.java
* plugins/Macros/About Plugin Macros

But they cannot be uploaded to an ImageJ2 installation because their file extensions are not recognized by the Updater. (I think!)

Figure out how to let these files upload as intended.