Expose API for getting # of consecutive retry failures

[scottgonzalez]

This will be used to track historical failures and alert on a threshold.

[scottgonzalez]

This can be as simple as a single shell command:

sqlite3 retry.db "SELECT COALESCE(MAX( tries ), 0) FROM retry; SELECT COUNT(*) FROM retry;"

Which outputs two lines, each with one number.
First line is number of consecutive failures.
Second line is number of pending retries.

[scottgonzalez]

Implemented in jquery/infrastructure@e32c2c199341f0ef226109480fb7475dc06e4244.