0.6.1 — updates you can actually see

0.6.1 — make the update mechanism visible and testable

update_plugins_github.com returned false when the installed version was
already current, which keeps the plugin out of both the response and the
no_update bucket. WordPress only offers the auto-update toggle for
plugins it has in one of them, so on a site where updates were wired up
correctly the plugins screen said otherwise. The filter now always
returns the payload and lets WordPress pick the bucket.
The 12-hour cache also ignored "Check again", so a freshly published
release stayed invisible for up to half a day. force-check now bypasses
it.