HealthKit extension added

Do a quick lint of CorePromise for all PLAT=macOS (#934)

* Verifies that we support CocoaPods for all Xcodes we claim
* Will fail for any warnings on any platform/Xcode combination
* Removes the `swift_version` from the Podspec as this makes CocoaPods unable to actually support all the Swift versions we support as well as refuse to even lint in CI for our chosen Swift version overrides

6.4.1: Merge pull request #927 from chrisscholly/bump-version

Bump version to `v6.4.1` to match latest release

6.3.5

Xcode 10 / Swift 4.2 support across all extensions.

6.2.9

Updates to CloudKit extension deployment targets to avoid warnings on newer platforms.

If you need older deployments, you will have to vendor the older versions of these files.

6.2.8

• Support for static libraries and CocoaPods

1.7.7

• Lightweight ObjC generics

6.2.7

Bump to 6.2.7

6.2.3: Added omitted `PMKRace` to `.podspec`

This doesn’t lint when Foundation subspec inc’d

Because `Promise<(Pipe, Pipe)>.print` confuses the compiler for Swift.print usage. This obv. is completely daft, but whatever.

6.2.2

Import PromiseKit/Foundation@3.0.4

6.2.1

• Alamofire — Support Custom Serializers (PromiseKit/PMKAlamofire@33c652a)
• Alamofire — Extended responseDecodable for JSONDecoder injection (PromiseKit/PMKAlamofire@ddf0e15)