feature/automatically_detect_target_format

[fkoh111]

Programmatically detect the target format when fetching a file. Seems like this info is part of the json:

{
    "id" : 15,
    "key" : "66b28eb8fa03c69157a68b6926acd02d6ad1406b",
    "status" : "initialising",
    "sandbox" : true,
    "created_at" : "2013-10-27T13:41:00Z",
    "finished_at" : null,
    "source_file" : {"id":2,"name":"portrait.gif","size":90571},
    "target_files" : [],
    "target_format" : "png",
    "credit_cost" : 1
}

https://developers.zamzar.com/docs