Public url for libffi submodule
Merge pull request #1 from rabovik/patch-1

Public url for libffi submodule
Adds class_implementProperty.
Allows user to implement getter or setter at compile time.
Removes libffi and replaced class_swizzleSelectorWithBlock with class_replaceMethodWithBlock. Fixes #2.
Fixes merge conflicts.
Minor cleanup.
Now using __attribute__((overloadable)) for class_implementProperty.
Improves class_implementProperty.
Migrates to SL namespace.
Updates README.
Release 0.0.2.
Updates SLObjectiveCRuntimeAdditions.podspec.
Introduces object_interposeBlockImplementation and object_interposeHiddenClass.
Typo.
Release 1.0.0.
Fixing memory leak.
Release 0.0.3.
Release 1.0.1.
Updating SLBlockDescription.