For the majority of Git LFS's lifetime, Git LFS objects have been
uploaded via HTTP and contained the header:
Content-Type: application/octet-stream
In [1], this changed and we began attempting to guess an appropriate
Content-Type header based on the first 512 bytes of the file being
uploaded.
This breaks some hosting platforms' implementation of this API, so let's
offer a way to disable this guessing to allow users to upload objects
again on affected implementations.
[1]: a1736293 (Merge pull request #3137 from
calavera/set_upload_content_type, 2018-07-23)
