Add overload of failure() that captures file/line
Add overload of failure() that captures file/line

Resolves #4.

LlamaKit/LlamaKit,ashfurrow/LlamaKit,Carthage/LlamaKit,Carthage/LlamaKit,ReactiveCocoa/LlamaKit,LlamaKit/LlamaKit,ashfurrow/LlamaKit,Carthage/LlamaKit,LlamaKit/LlamaKit,ashfurrow/LlamaKit,ReactiveCocoa/LlamaKit