* Fixes NPE when no outputDir is set
* Fix behaviors of default values for values not provided by user
* Easier handling of default behavior in settings.
* Fixes for dynamic config deserialization (specifically, ruby client sample fix)
* Tests for WorkflowSettings (defaults, modified defaults, nulls)
* Test modification of WorkflowSettings defaults for both class constructor and builder
* 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
