add scraper to diagnose intermittent problems

This script scrapes cdash results for each submitter over time
so that you can see problematic machines and tests that fail some
of the time.

Change-Id: Idbe3c7cf53bc413e632e9d8f763f697a49a7ac30
Merge topic 'add_cdash_history_scraper' into master

b36cfc7e add scraper to diagnose intermittent problems