Cobertura XML output format doesn't exactly match real cobertura format for class names, method names

See [https://github.com/scoverage/scalac-scoverage-plugin/pull/133#discussion_r46520752]
and [https://github.com/scoverage/scalac-scoverage-plugin/issues/27#issuecomment-161542359]

The class name and method name are wrong in the `scoverage` output in "cobertura" XML output mode, when compared to a real Cobertura coverage run.
