Jenkins integration improvements/bugfixes (round 1)

- send e-mail on Jenkins added comment only, when there were checkstyle/pmd warnings found
- determine commit identifier from Jenkins build information (commit that triggered the build)
- match file paths in warnings to commit file paths via "substr"
- store warnings using absolute file path in repository, not relative working copy path
- PMD warnings were stored in place of Checkstyle warnings
- output commit information back from API call
- don't process synthetic authors for PHIDs, when rendering audit inline comments