Fixing error printing RHS

[houshuang]

Not sure if this is the right place to fix this, but here is my error message before the commit:

  2) test lists work - three lists (XmlrpcTest)
     test/sax_test.exs:52
     ** (Amrita.FactError) Expected:
          {:ok, [[[12, "Egypt", false, -32]], [[12, "Egypt", false, -31]], [12, "Egypt", false, -33]]} |> test lists work - three lists
     stacktrace:
       lib/amrita/message.ex:10: Amrita.Message.fail/3
       test/sax_test.exs:52

.

  3) test lists work - two lists (XmlrpcTest)
     test/sax_test.exs:51
     ** (Amrita.FactError) Expected:
          {:ok, [[[12, "Egypt", false, -32]], [12, "Egypt", false, -31]]} |> test lists work - two lists
     stacktrace:
       lib/amrita/message.ex:10: Amrita.Message.fail/3
       test/sax_test.exs:51

and here after

  2) test lists work - two lists (XmlrpcTest)
     test/sax_test.exs:51
     ** (Amrita.FactError) Expected:
     {:ok, [[[12, "Egypt", false, -32]], [12, "Egypt", false, -31]]} |> {:ok, [[12, "Egypt", false, -31], [12, "Egypt", false, -32]]}
     stacktrace:
       lib/amrita/message.ex:10: Amrita.Message.fail/3
       test/sax_test.exs:51
...
  3) test lists work - simple list (XmlrpcTest)
     test/sax_test.exs:50
     ** (Amrita.FactError) Expected:
     {:ok, [[12, "Egypt", false, -31]]} |> {:ok, [12, "Egypt", false, -31]}
     stacktrace:
       lib/amrita/message.ex:10: Amrita.Message.fail/3
       test/sax_test.exs:50

Here is the test-suite. https://github.com/houshuang/elixir-xmlrpc/blob/sax-nested/test/xmlrpc_test.exs

[josephwilk]

Looks nice, happy to merge. Just curious why the build is failing.