Cloverage custom reporter that generates Cobertura XML coverage reports.

Usage (CLI):
  lein cloverage --custom-report cloverage.coverage.cobertura/report

Usage (project.clj):
  :cloverage {:custom-report cloverage.coverage.cobertura/report}

Writes 'cobertura.xml' to the cloverage output directory (default: target/coverage/).

The Cobertura XML schema maps Clojure namespaces to packages and classes:
  - Package: all but the last segment of the namespace (e.g. 'example.util' -> 'example')
  - Class:   the full namespace string (e.g. 'example.util')
  - File:    the source path relative to the project root