Improve com.tc.util.factory.AbstractFactory

[ljacomet]

This code does some form of service loading without using a java.util.ServiceLoader.
However it has one major difference: it only supports files where the first line is a valid FQN classname. Anything else makes it fail, although that line can be followed by pretty much anything which will be ignored.

We should improve it in either of the following ways:

• Delegate to the standard ServiceLoader system
• Improve the file parsing to be fully compatible with ServiceLoader file syntax.