Code that demonstrates unexpected behavior with regards to completedChangesCount of replicator observer.
Fixed an assertion-failure when a _bulk_get download can’t parse a JSON doc

Fixes #232
Fixes #271
Merge branch 'replicator_observer_issue' of github.com:couchbase/couchbase-lite-ios
Don’t set replication progress to 0/0 when stopping

Instead the progress should remain the way it was.
Also, improved Traun’s great new test for verifying that progress counts make sense.
Fixes #274
64bit build settings