`test_prepare_multipart` fails in non Debian environments since
Debian installations map the file ending `.key` to the MIME type
`application/pgp-keys`, which is not IANA conformant. This commit
explicitly sets the corresponding file type to
`application/octet-stream` and adjusts the expected serialized
result.
* Add multipart/form-data functionality
* Fix some linting issues
* Fix error message
* Allow filename to be provided with content
* Add integration test
* Update examples
* General improvements to multipart handling
* Use prepare_multipart for galaxy collection publish
* Properly account for py2 vs py3, ensuring no max header length
* Address test assumptions
* Add unit tests
* Add changelog
* Ensure to use CRLF instead of NL
* Ignore line-endings in fixture
* Consolidate code, add comment
* Bump fallaxy container version
* ci_complete
