[CB-2790] added splice function to header writer: accepts jpeg as NSData, and splices in exif data specified by a string
[CB-2790] removed old splice code, replaced with JpegHeaderWriter api calls
[CB-2537] Implement streaming downloads for FileTransfer
[CB-51] Added httpMethod for file transfer options (defaults to POST)
[CB-2190] Allow FileTransfer uploads to continue in background
[CB-1518] Request content length in parallel with download for gzipped content