Fix Mappable extension

It's need to make it public.

Author: Rafael da Silva Ferreira

JSONStub.podspec

@@ -8,7 +8,7 @@
 
 Pod::Spec.new do |s|
   s.name             = 'JSONStub'
-  s.version          = '0.1.4'
+  s.version          = '0.1.5'
   s.summary          = 'Use JSONStub to easily load JSON files into your Mappable objects.'
 
 # This description is used to generate tags and improve search results.

JSONStub/Classes/Mappable.swift

@@ -8,7 +8,7 @@
 
 import protocol ObjectMapper.Mappable
 
-extension Mappable {
+public extension Mappable {
     init?(fromFileName file: String) {
         guard let json = file.fileDictionary() else { return nil }