Merge pull request #14 from uber/execution-accessibilty

Fix execution classes accessibility

Merge pull request #13 from uber/execution-inheritance

Update AbstractTask to be open for inheritance

Merge pull request #12 from uber/execution-master

Add task execution package

Merge pull request #9 from uber/fix_nscondition_loop

Fix CountDownLatch usage of NSCondition

Merge pull request #6 from uber/release-carthage_project-master

Add Xcode project to support Carthage

Update README.md

Merge pull request #1 from uber/structure-fix_package_manifest-master

Remove copyright from package manifest