Fix Mac use of PromiseKit
Fix Mac use of PromiseKit

Tag 0.9.15.3

Fixes #74
pgherveou/PromiseKit,mxcl/PromiseKit,pgherveou/PromiseKit,mxcl/PromiseKit,mxcl/PromiseKit,allen-zeng/PromiseKit,allen-zeng/PromiseKit,pgherveou/PromiseKit