Adjust code to Weka 3.7.11 version:

- Remove FastVector use.
- Use Object instead of String when enumerating values of the class attribute.
Update hack to add the custom classifier FastRandomForest.

Given the new version of WEKA, we need to add now a call to PluginManager.addFromProperties()
Remove unused class
Comment unused variable
As pointed out by Curtis, change fiji pom version to 2.0.0.beta-1-SNAPSHOT.

This will make the update in the weka version effective.
Release version 2.1.0.

Majors changes:
- Update WEKA version to 3.7.11
- Increase maximum number of classes to 10
- Trace colors are selected by golden angle
- Catch out of memory exception when training
- Add unit tests designed by Johannes Schindelin
- Speed up color features calculation
- Display result image with original class values (0, 1, 2...) and LUT
- Fix minimux size of the GUI to prevent strange behaviors when reducing the size of the window