Support for the new watchos platform

[neonichu]

Fixes some issues with the newly added watchos platform. This lays the groundwork for supporting watchOS as a new platform in CocoaPods.

Things yet to be addressed:

• Specs
• Changelog
• Pods integrated into watchapp2 and watchkit2-extension targets should automatically be build for watchOS
• Add watchOS example (unused for now, because Travis doesn't have Xcode 7)

See also CocoaPods/Core#249 and CocoaPods/Xcodeproj#272

[neonichu]

See https://github.com/neonichu/native-watchOS-example for an example on how to try this out.

[segiddins]

This is a backwards incompatible change?

[neonichu]

Possibly - might be a better idea to only use Foundation for watchos targets.

[mrackwitz]

Regarding specs:
Once Travis supports Xcode 7, we should definitively add an example for watchOS to ensure that our produced integrations can be actually build on that platform as well. But you could add an example already now, just ensure that it doesn't fail rake examples:build when Xcode 7 is not available, so we can test that at least locally.
Beside that we should cover that also by an integration spec, I think we could update e.g. install_multiple_targets.

[neonichu]

@mrackwitz Will add an example, not sure what the integration spec should actually test, though. Since the changes on this repo are minimal, it seems a bit redundant.

[kylef]

Perhaps we should leave this empty for new platforms?

Re: #1746

[segiddins]

👍

[neonichu]

Good idea 👍

[mrackwitz]

Foundation must be imported as long as the FOUNDATION_EXPORT macro is used by the umbrella header.

[kylef]

In that case, shouldn't the umbrella header import Foundation and not the pch file?

[neonichu]

Pods integrated into watchapp2 and watchkit2-extension targets should automatically be build for watchOS

Seems like this is generally not done and it is up to the user to define the correct platform for the watchOS targets inside their Podfile.

[segiddins]

@neonichu isn't that done via target introspection already?

[neonichu]

@segiddins I think it's supposed to be done, but doesn't actually function.

[neonichu]

OK, this should be merge-able now 🎉

[segiddins]

Should already be done in TargetInspector#compute_platform

[segiddins]

👍

[neonichu]

⌚ 🎉

[9JX]

I would like to move watch target's resource and storyboard as a pod library, but when I
compile error “error: watchOS storyboards do not support target device type "mac””。
I found Pods-JDWatch-resources.sh script TARGET_DEVICE_ARGS not include watch，Is cocoaPods not supported like this？please help me！