Limit FindBugs diff errors in JIRA comments

In OOZIE-1986 the FindBugs diff functionality was introduced. At times, however, there are cases when it's painful that we print out each and every FindBugs error (the ones considered mandatory to be fixed) to the JIRA comment.

We'll limit the FindBugs errors to be displayed within a module (let's say, top 5 from a module). This limitation will only be valid for TEST-SUMMARY.jira and TEST-SUMMARY.txt - for TEST-SUMMARY-FULL.jira and TEST-SUMMARY-FULL.txt the output remains unchanged.