Correctly format unicode token parser exceptions

Fixes #107.

Author: devinus

lib/poison/parser.ex

@@ -23,7 +23,7 @@ defmodule Poison.ParseError do
   end
 
   defp escape(token) do
-    {value, _} = Identifier.escape(<<token>>, ?\\)
+    {value, _} = Identifier.escape(<<token::utf8>>, ?\\)
     value
   end
 end
@@ -350,7 +350,7 @@ defmodule Poison.Parser do
   ## Errors
 
   defp syntax_error(<<token::utf8>> <> _, pos) do
-    raise %ParseError{pos: pos, value: <<token>>}
+    raise %ParseError{pos: pos, value: <<token::utf8>>}
   end
 
   defp syntax_error(_, pos) do

test/poison/parser_test.exs

@@ -88,6 +88,10 @@ defmodule Poison.ParserTest do
       parse!(~s("𝄞))
     end
 
+    assert_raise ParseError, "Unexpected token at position 0: á", fn ->
+      parse!(~s(á))
+    end
+
     assert_raise ParseError, "Unexpected token at position 0: \\x1F", fn ->
       parse!(~s(\u001F))
     end