A standard from has no trailing whitespace after a content-disposition line like so: "Content-Disposition: form-data; name="data";" however when using the extra params of Android FileTransfer a space is added on the end "Content-Disposition: form-data; name="data"; "
This fix simply removes the trailing whitespace.
FileTransfer returns FILE_NOT_FOUND_ERR on http 500 error
For some reason on Android if you do a getInputStream() on a HTTP Connection and the server returns a 500 error it will report a FileNotFoundException. Catching this exception and throwing an IOException so that we can report a more accurate error in JavaScript.