Single sign out support

[endel]

As already discussed on pull request #48, here is my fork of @jeremyhaile's implementation, which works for the session stores:

ActiveRecord::SessionStore
ActionDispatch::Session::CacheStore
RedisStore

[nbudin]

I really like this refactoring. Great work both @jeremyhaile and @endel; once someone has tested it in a real world setup I'd love to get this merged.

[geoffroh]

@endel @nbudin This looks good to me, works well on a CAS setup i'm using. Thank you.

[nbudin]

Great, thank you everyone! Just merged to master; it passes tests for me locally but I'm waiting to see if it works on Travis before doing a release.

[stephenlam]

failing on Travis?

[nbudin]

The current Travis results aren't actually with this changeset. It seems like Travis is hung up right now on running new stuff; hopefully it will be back soon.

Even when it does start running these tests, it's likely to come up as an overall failure, because the tests are broken in certain environments (the very oldest versions of Ruby and Rails) and I haven't been able to fix them. (Patches welcome!) But I want to at least see that we're still passing in the environments in which we were before.

[nbudin]

OK, it looks like Travis is still having some issues, but we've got a passing build on recent versions of Devise (which is roughly equivalent to where we were before this pull request). I don't love being in this state, but given that we have a report of it working in practice, and we know that the current implementation has problems in practice, I'm going to release this. Will update here when it's done.

[nbudin]

And it's out. Version 1.2.0, with brand shiny new single sign out support.

Serious, major thanks to everyone who contributed here. This is by far the most opaque part of the project to me, having no easy way to test it, so I really appreciate everyone's work.