Append to Existing File

[dborncamp]

Currently, if a file already exists in Data the SDK cannot append to that file. This is because when appending to a file, Data sees the file as a directory with the name of the file instead of just a file. In order to make this work, the file will need to be removed and a directory of its name needs to take its place then that original file needs to be uploaded into that directory as the first part.

Currently, if this is tried it will fail with a warning that this is not implemented.