Ability to write already compressed image data

Created by: isosc

When importing jpg images into adios, we want to avoid decompressing and then recompressing due to the loss of quality that would result. Instead, it should be possible to call put (or write in the hl python api) and pass a buffer containing the already compressed data (along with any necessary compression related metadata). This is particularly useful for large tiled images such as TCGA (cancer images).