Allow tests to proceed as soon as the payload changes, instead of always having to wait for a timeout

[#6455 state:committed]
Signed-off-by: NSantiago Pastorino <santiago@wyeworks.com>

Signed-off-by: NSantiago Pastorino <santiago@wyeworks.com>

Mismatches between migrations and constants have nothing to do with
pluralization rules or model names. The mismatch happens between
the camelization of the filename minus timestamp, and the name of
the migration class itself.

This reverts commit 1c21f75f.

Signed-off-by: NXavier Noria <fxn@hashref.com>