Merge pull request #128 from demonar/swift2.3

migrated project to swift 2.3

Add View based HUD

Update PKHUD.podspec to Version 4.0 using Swift 3

Retain Cycle. Resolves #93.

Podspec Bump.

Bumping Podspec.

Resolves issue #72.

- Porcelain and Plumbing APIs.

Update PKHUD.podspec

iOS 8 Fix.