avoid the use of single-argument Class.forName()

In dynamic class loading environments such as OSGi, the use of the single-argument `Class.forName()` method is highly discouraged. See e.g. http://techblog.ralph-schuster.eu/2013/11/04/the-class-forname-problem/

This pull request consolidates the two usages of `Class.forName()` into a new `loadClass()` method which uses the three-argument method.