WatchOS1 storyboard not being compiled correctly

Created by: rmaz

When compiling a watchOS1 target, the app crashes at runtime with:

(Error) WatchKit: <SPApplicationDelegate.m -[SPApplicationDelegate application:didFinishLaunchingWithOptions:]:611> Error - unable to find interface description file Interface.plist for com.blah.amazingapp.watchkitapp. Exiting.

It seems that when Xcode is compiling the storyboard for the watch app, it dispenses with the .storyboardc containing folder, and just puts the generated plist files during compilation into the app bundle. ie If we have an Interface.storyboard, Xcode generates:

Base.lproj
|-> Interface.plist
|-> Interface-notification.plist

whereas buck is outputting:

Base.lproj
|-> Interface.storyboardc
      |-> Interface.plist
      |-> Interface-notification.plist

Looks like the issue is AppleBundle.java:708, the platform name is being checked to correctly compile the storyboard, but we also need to check for legacy_watch flavor.