Rack gets a newline at the end of the content_type in certain instances:…

Rack gets a newline at the end of the content_type in certain instances: 'image/jpeg\r' which causes S3 to be unable to accept the file. Fixes #817

lib/paperclip/io_adapters/uploaded_file_adapter.rb

@@ -15,7 +15,7 @@ module Paperclip
 
     def cache_current_values
       @original_filename = @target.original_filename
-      @content_type = @target.content_type
+      @content_type = @target.content_type.to_s.strip
       @size = File.size(@target.path)
     end
   end

test/io_adapters/uploaded_file_adapter_test.rb

@@ -10,7 +10,7 @@ class UploadedFileAdapterTest < Test::Unit::TestCase
 
         @file = UploadedFile.new(
           :original_filename => "5k.png",
-          :content_type => "image/png",
+          :content_type => "image/png\r",
           :head => "",
           :tempfile => tempfile,
           :path => tempfile.path