aws-sig4 requires expires_in to be an int

refs RD-4078
Test Plan
Make sure we can still use crocodoc, and canvadocs

Change-Id: I0fcc8315ca65b96511695facc4a3fa59034256b9
Reviewed-on: https://gerrit.instructure.com/113402
QA-Review: Caleb Guanzon <cguanzon@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Tested-by: Jenkins
Product-Review: Caleb Guanzon <cguanzon@instructure.com>

gems/attachment_fu/lib/attachment_fu/backends/s3_backend.rb

@@ -247,6 +247,11 @@ module AttachmentFu # :nodoc:
       def authenticated_s3_url(*args)
         thumbnail = args.first.is_a?(String) ? args.first : nil
         options   = args.last.is_a?(Hash)    ? args.last  : {}
+        unless options[:expires_in].nil?
+          if options[:expires_in].is_a? ActiveSupport::Duration
+            options[:expires_in] = options[:expires_in].to_i
+          end
+        end
         s3object(thumbnail).presigned_url(:get, options)
       end
 

spec/models/attachment_spec.rb

@@ -72,6 +72,19 @@ describe Attachment do
     end
   end
 
+  context "authenticated_s3_url s3_storage" do
+    before :each do
+      s3_storage!
+    end
+
+    it "should give back a signed s3 url" do
+      a = attachment_model
+      s3object = a.s3object
+      expect(a.authenticated_s3_url(expires_in: 1.day)).to match(/^https:\/\//)
+      a.destroy_permanently!
+    end
+  end
+
   def configure_crocodoc
     PluginSetting.create! :name => 'crocodoc',
                           :settings => { :api_key => "blahblahblahblahblah" }