Allow iOS 7.0 for Cocoapods

Snap.podspec

@@ -8,7 +8,7 @@ Pod::Spec.new do |s|
   s.social_media_url = 'http://twitter.com/robertjpayne'
   s.source = { :git => 'https://github.com/Masonry/Snap.git', :tag => '0.0.2' }
 
-  s.ios.deployment_target = '8.0'
+  s.ios.deployment_target = '7.0'
   s.osx.deployment_target = '10.9'
 
   s.source_files = 'Snap/*.swift'