Renamed 'drill-instructor' to 'checksum-verifier'.
Test for warning in CrawlConfig.
Fallout from renaming drill-instructor to checksum-verifier.
test_read_warn was failing after test_read_include because of a file
left behind by the first test. Changed the second test to use a
different filename.
Added dbname to DBIerror so we can tell which database we're failing
on.
Bail if we're getting fast, repeated exceptions (more than 3 in five
seconds).
Everybody needs to use the same database name.