Catching up elixir v1.0

Hi, it's a very nice set of examples. I'm just trying to update some of the examples for elixir v1.0 (as in #6). 
Basically, it's just update for some deprecation (lc or defrecord), but some specific notes are the following.

- 08-process-ring.exs
    - Process.spawn_monitor is changed to Kernel.spawn_monitor

- 13-card-deck.exs
    - doctest is removed as there seems no doctest is defined.

```
** (ExUnit.DocTest.Error) could not retrieve the documentation for module Deck. The module was not compiled with documentation or its beam file cannot be accessed
    (ex_unit) lib/ex_unit/doc_test.ex:345: ExUnit.DocTest.extract/1
    (ex_unit) lib/ex_unit/doc_test.ex:168: ExUnit.DocTest.__doctests__/2
    13-card-deck.exs:42: (module)
```

- 14-spades.exs
    - separate function with both default value and guard.
      (wait_for_plays/2 is originally defined, but not added as it's not used for avoiding warning)

```
** (CompileError) 14-spades.exs:102: defp wait_for_plays/3 has default values and multiple clauses, define a function head with the defaults
    (elixir) src/elixir_def.erl:328: :elixir_def.store_each/7
    (elixir) src/elixir_def.erl:91: :elixir_def.store_definition/9
    14-spades.exs:102: (module)
    14-spades.exs:27: (file)
```

- 15-quine.exs
    - Escaped closing `)` for avoiding compile error (couldn't find the exact reason, but assume it's some behavioral change in sigil).

```
** (TokenMissingError) 15-quine.exs:5: missing terminator: " (for string starting at line 3)
    (elixir) lib/code.ex:316: Code.require_file/2
```