* Add support for enum schemas and properties to the rust generator
Also:
* Skip serializing a field with serde if it's optional and empty
* Fix borrow checker error when using &std::path::Path (should be std::path::PathBuf)
* Add script to generate sample with rust-reqwest
* Regenerate petstore sample for both rust targets
* Remove go code from README.md
* Fix formatting of serde skip_serializing_if attribute
* Port of PR https://github.com/swagger-api/swagger-codegen/pull/8804.
* Correction of conflict with PR #528 (missing template file).
* Add rust-reqwest samples to Circle CI tests.
* Add integration test pom.xml file with launcher to trigger cargo execution.
* Deduplicate Maven project name.
* Fix "api_key" header for Petstore.
* Better API key management.
* Fix query param for lists of objects other than strings (numbers, etc.).
* Update to reqwest 0.9, and refactor of header management (using reqwest transition feature).
* Merge scripts generating rust-hyper and rust-reqwest samples.
* Consistent full stops.
* Use raw variables in all Rust mustache templates.
* Replace production build in CI with a quick simple check.
* Update samples.
* Finish Reqwest 0.9 migration (removing "hyper 0.11" transition feature).
* Configuration implements Default trait.
* API template reorganized: HashMap is not required anymore.
* Revert "Merge scripts generating rust-hyper and rust-reqwest samples."
This reverts commit 970f996566a740045f2a986fd70fc70f11952925.
* Remove deprecated "-XX:MaxPermSize" java arg.
