All tests use the same database instance (Cloudant or CouchDB)
Retry revisions which fail to replicate with a 412

This indicates something is confused with attachments stubs. We can
safely resend using a multipart/related POST which includes all the
current attachment data. This is inefficient, but allows us to
safely replicate in the face of revpos bugs and matches CouchDB
behaviour.
Add Rake command to run replication acceptance tests on simulator
Remove spurious comment.
Add a test which will always cause a 412 to check our retry logic
Merge pull request #31 from cloudant/31142-retry-on-412-error

31142 Retry sending revisions if we get a 412 missing_stub response for a document