Update podspec to publish on cocoapods

Author: gsempe

DBAlertController.podspec

@@ -0,0 +1,16 @@
+Pod::Spec.new do |s|
+  s.name             = "ONCEAlertController"
+  s.version          = "1.0.0"
+  s.summary          = "A UIAlertController subclass that's independent of the view controller it's presented from."
+  s.homepage         = "https://github.com/OnceApp/ONCEAlertController"
+  s.license          = 'MIT'
+  s.author           = { "Guillaume Sempe" => "guillaume@getonce.com" }
+  s.source           = { :git => "https://github.com/OnceApp/ONCEAlertController.git", :tag => s.version.to_s }
+  s.social_media_url = 'https://twitter.com/oncetheapp'
+
+  s.platform      = :ios, '10.0'
+  s.swift_version = '4.1'
+  s.requires_arc  = true
+
+  s.source_files = 'Source/*.swift'
+end