Fixed ClasspathResolverTest (order of enclosed classes is reversed)

The test cases:

1) org.jadira.scanner.classpath.ClasspathResolverTest#simpleExecution
2) org.jadira.scanner.classpath.ClasspathResolverTest#simpleExecution2

fail because the order of the enclosed classes from `firstClass.getEnclosedClasses()` is reversed:
            assertEquals("JInnerClass[name=org.jadira.scanner.classpath.A$1,enclosingClass=JClass[name=org.jadira.scanner.classpath.A]]", firstClass.getEnclosedClasses().get(0).toString());

I fixed this by comparing sets of class names.