Commit best practices

specify issue, files modified, and summary

• specify related issue number and title
• optionally precede first line with "Fix for" or the like
• specify source file changed, preceded by *
• summarize changes to each source file, preceded (usually) 4 spaces

for example, changeset r6912

[HER-1796] H3: interval rescheduling becomes erratic after URI rescheduled more than maxRetries times
* CrawlURI.java
    improve comments for fetchAttempts methods
    (resetForRescheduling) added to clear per-scheduling state
* WorkQueueFrontier.java
    call resetForRescheduling just before scheduling-at-specific-time
* FrontierJournal.java, AbstractFrontier.java
    renamings: prefer 'reenqueue' instead of 'reschedule' for describing simple (non-timed) retries