title: Writing to AWS S3 using python library s3fs fails with EntityTooLarge
body: <p>I know that there is a limit in the AWS S3 API for uploading files bigger than 5 gb. In <code>boto3</code> I should use <code>multipart</code></p>
  
  <p>I am trying to configure the <code>S3File</code> object in <code>s3fs</code> to do the same, but I can't figure it out.</p>
  
  <p>I am using (as an example of the error) a very basic code:</p>
  
  <pre><code>import s3fs
  
  s3 = s3fs.S3FileSystem()
  
  with s3.open("s3://bucket/huge_file.csv", "w") as s3_obj:
     with open("huge_file.csv") as local_file
         s3_obj.write(local_file.read())
  </code></pre>
  
  <p>Where <code>huge_file.csv</code> has a size > <code>5Gb</code>. </p>
  
  <p>The error I am getting is </p>
  
  <pre><code>...
  botocore.exceptions.ClientError: An error occurred (EntityTooLarge) when calling  the PutObject operation: Your proposed upload exceeds the maximum allowed size
  
  ...
  
  File ... /s3fs/core.py" line 1487, in __exit__
  
  self.close()
  
  File ... /s3fs/core.py" line 1454, in close
  </code></pre>
  
  <p>So, the question is How (if it is possible) can I setup <code>s3fs</code> to upload files bigger than <code>5Gb</code> (How shoud Iconfigure it to do multipart uploading)?</p>