(#1734) - leveldb simultaneus write race condtions
(#1734) - leveldb doc writing race conditions
(#1860) - Fix info.doc_count for leveldb
(#1809) - proper through stream for all docs, and handle errors
(#1898) - don't wait until we have all the changes before calling onChange
(#1910) - more fully cancel changes
(#1460) - always cancel changes when db is destroyed