Make sure no newline from type_from_file_command

This relates to #817

lib/paperclip/io_adapters/abstract_adapter.rb

@@ -27,6 +27,5 @@ module Paperclip
       mime_type = "application/x-#{type}" if mime_type.match(/\(.*?\)/)
       mime_type
     end
-
   end
 end

test/io_adapters/abstract_adapter_test.rb

+require './test/helper'
+
+class AbstractAdapterTest < Test::Unit::TestCase
+  class TestAdapter < Paperclip::AbstractAdapter
+    attr_accessor :path, :original_file_name
+
+    def content_type
+      type_from_file_command
+    end
+  end
+
+  context "content type from file command" do
+    setup do
+      Paperclip.stubs(:run).returns("image/png\n")
+    end
+
+    should "return the content type without newline" do
+      assert_equal "image/png", TestAdapter.new.content_type
+    end
+  end
+end