0.2.2 minimum compatible iOS, fix chain issue

• Updates the minimum compatible iOS version to 8.0
• Fixes an issue where a chained, pending Deferred would never resolve

UIImage/NSData Extensions

Added a couple extensions for easily fetching a Deferred UIImage and NSData and offloading these tasks onto a separate queue.

Swift 1.2

v0.2.0

Swit 1.2 compatibility, bump version to 0.2.0

Promise chaining, Cocoapods support, preliminary testing

v0.1.2

Fix source files in podspec

v0.1.1

Cean up tests

v0.1

• Basic promises
• Commented source
• Partial test coverage
• Basic usage documentation in README