issue number #157

Initial port of iOS _bulk_get code

issue number #157

Additional updates

issue number #157 latest patch

issue number #157 - resolved failing unit tests

issue number #157, updates to BulkDownloader

issue number #157, improved _bulk_get body generation

Fix compile errors related to changes in issue #269

Now accepts multipart/mixed in _bulk_rev response

No longer accept gzip response from SG, improved checks for application/json type for docs with no attachments

issue number #157

Removed commented out code line
issue number #157

Removed expensive log call