cactus-report does not show stack trace on failures/errors

When you generate the cactus report using maven, it doesn't show the stack trace of the test cases that fails, only its messages.

I'm providing a simple patch that fix this issue. This patch is a quick hack, though - ideally, the cactus-report should have the same structure as the junit-report, i.e., with a specific section for 'Failure Details'.