Add ability to set :headers key.

README.md

@@ -62,7 +62,8 @@ class Notifier < SendWithUsMailer::Base
             bcc: [{:address => "[email protected]"}, {:address => "[email protected]"}],
             version_name: 'version-A',
             locale: 'en-US',
-            files: ["/path/to/file"]
+            files: ["/path/to/file"],
+            headers: { 'header-name' => 'header-value' }
         )
     end
 end

lib/sendwithus_ruby_action_mailer/mail_params.rb

@@ -13,6 +13,7 @@ def initialize #:nodoc:
       @version_name = ""
       @locale = ""
       @files = []
+      @headers = {}
     end
 
     def assign(key, value) #:nodoc:
@@ -44,6 +45,8 @@ def merge!(params={}) #:nodoc:
           @locale = value
         when :files
           @files.concat(value)
+        when :headers
+          @headers.merge!(value)
         end
       end
     end
@@ -65,7 +68,8 @@ def deliver
         esp_account: "",
         version_name: @version_name,
         locale: @locale,
-        files: @files
+        files: @files,
+        headers: @headers
       )
     end
   end

test/lib/sendwithus_ruby_action_mailer/integration_test.rb

@@ -28,7 +28,8 @@ def example_email
              from_address: '[email protected]',
              from_name: 'asender',
              reply_to: '[email protected]',
-             version_name: 'v2'
+             version_name: 'v2',
+             headers: { 'header-name' => 'header-value' }
       end
     end