Bug 55802: Batch database title requests in rt-testing server

Crashers have been separated from reported errors, there's both a counter
for latest commit crashers on the main page and a new page /crashers with
a list of all the known crashers (which get removed when a new commit
finishes correctly).

Change-Id: I67166ff0d057c622ea18e14bb668b6fb9a55e937
Merge "Bug 55802: Batch database title requests in rt-testing server"