Retry configure/verify on transient chutney failures
chutney occasionally fails to bootstrap or verify. Sometimes, and on some platforms / machines, bootstrap is slower than we expect.
We should either: fix intermittent failures (legacy/trac#16951 (moved)), or lengthen the default sleep time (this ticket), or retry up to N times (argument) (this ticket) with increasing sleep times (this ticket), or implement a chutney command that finds out whether the network has finished bootstrapping (legacy/trac#16950 (moved)).
Easy fixes are to: make the default sleep time 30 seconds; retry verify at 45 and 60 seconds before giving up (args for interval and number of retries); and then retry once from the start with a new network in case of chutney configure / launch failure (arg for number of reconfigures). This will make it a maximum of 4.5 minutes before the test fails, after 3 x 2 retries.