[FIXED] Fixed crash caused by non-UTF8 chars in design documents.
[FIXED] Fixed TypeError when setting revision limits on Python>=3.6.
[FIXED] Fixed the exists() double check on client.py and database.py.
[FIXED] Fixed Cloudant exception code 409 with 412 when creating a database that already exists.
[FIXED] Catch error if throw_on_exists flag is False for creating a document.
[FIXED] Fixed /_all_docs call where keys is an empty list.
[FIXED] Issue where docs with IDs that sorted lower than 0 were not returned when iterating through _all_docs.