Add podspec

Puree.podspec

@@ -0,0 +1,11 @@
+Pod::Spec.new do |s|
+  s.name         = "Puree"
+  s.version      = "3.0.0"
+  s.summary      = "Awesome log collector"
+  s.homepage     = "https://github.com/cookpad/Puree-Swift"
+  s.license      = { :type => "MIT", :file => "LICENSE" }
+  s.authors      = { "Tomohiro Moro" => "[email protected]", "Kohki Miki" => "[email protected]" }
+  s.platform     = :ios, "10.0"
+  s.source       = { :git => "https://github.com/cookpad/Puree-Swift.git", :tag => "#{s.version}" }
+  s.source_files  = "Sources/**/*.{h,swift}"
+end