Semanitcally import Foundation rather than Cocoa
Semanitcally import Foundation rather than Cocoa

Cocoa/Cocoa.h doesn't exist on iOS and all this header file needs is
some exports from Foundation.

SwiftGit2/SwiftGit2,mattrubin/SwiftGit2,mattrubin/SwiftGit2,SwiftGit2/SwiftGit2