Fix OpenAPITools#1424 [SWIFT4] Date Encoding Issues (OpenAPITools#1442)

Ensure the same date format string is used throughout the generated code (use the one set in Configuration.swift).

Ensure the same date formatter options are used when encoding dates as well as decoding dates. If a consumer has set their own date formatter on CodableHelper, use that when encoding dates too.

Adds DateFormatTests to the SWIFT4 unit tests.

Updates the SWIFT4 petstore samples

3.3.2 release (OpenAPITools#1353)

* prepare 3.3.2 release

* update script to remove outdated reference

Prepare 3.3.1 patch release (OpenAPITools#1247)

* release_version_update

* comment out ensure up to date

* release_version_update_docs

* update release table

3.3.0 release (OpenAPITools#1153)

* update using release_version_update

* comment out ensure up to date script

* update using release_version_update_docs

* remove current master

Prepare 3.2.3 release (OpenAPITools#935)

* update release version, disabled ensure up to date script

* update release table

* update stable version to 3.2.3

* update samples/meta-codegen/lib/pom.xml and release_version_update.sh

3.2.2 release (OpenAPITools#869)

* run bin/utils/release_version_update.sh

* comment out ensure-up-to-date script

* run bin/utils/release_version_update_docs.sh

* fix link to lc3

3.2.1 release (OpenAPITools#807)

* 3.2.1 release

* roll back incorrect change to link

* update doc

* update 3.1.2 release

* Fix version table

3.2.0 release (OpenAPITools#744)

Release 3.1.2 (OpenAPITools#647)

Release 3.1.1 (OpenAPITools#588)