patch: add available in SKProductExtensions.swift

release: v5.1.0 (SwifterSwift#713)

5.0.0 (fastlane)

Update the CHANGELOG to correctly display what has been changed for t…

…he latest version (SwifterSwift#569)

* Update the CHANGELOG to correctly display what has been changed for the latest version
Close the version to create a public release

* Update README and podspec for v4.6.0

Update for Swift 4.2 and Xcode 10 support (SwifterSwift#562)

* Updating Code base and iOS Unit Tests.

* Updating MacOS tests

* Update travis image.

* Updating some extensions.

* Updating pod spec swift version

* Updating swift version

* Fixing indentation on some files.

* Indenting.

* Indenting some files.

* Running swiftlint autocorrect --format

* Workaround cocoapods issue

* Updating spec, readme and changelog for new version.

* Removing toggles since they are stdlib now.

* Deprecating random extensions in favor of the natives.

* Updating arc4_random usages.

* Removing prior SwifterSwift 4.2.0 version deprecated version.

Merge pull request SwifterSwift#510 from SwifterSwift/v4.4

v4.4

Signed numeric (SwifterSwift#434)

v4.2.0 (SwifterSwift#417)

* v4.2.0

* updating readme

* update readme.

v4.1.1 (SwifterSwift#356)

v 4.1.0