Added very basic koans for integers

lib/koans/16_integers.ex

@@ -0,0 +1,37 @@
+defmodule Integers do
+  require Integer
+  use Koans
+
+  @intro "Integers"
+
+  koan "Are you odd?" do
+    assert Integer.is_odd(3) == ___
+  end
+
+  koan "Actually you might be even" do
+    assert Integer.is_even(4) == ___
+  end
+
+  koan "Let's grab the individual digits in a list" do 
+    individual_digits = Integer.digits(58127)
+    assert individual_digits == ___
+  end
+
+  koan "Oh no! I need it back together" do 
+    number = Integer.undigits([1, 2, 3, 4])
+
+    assert number == ___
+  end
+
+  koan "I think I need my number as a char" do 
+    char_digit = Integer.to_char_list(7)
+
+    assert char_digit == ___
+  end
+
+  koan "Actually I want my number as a string" do 
+    string_digit = Integer.to_string(1234)
+
+    assert string_digit == ___
+  end
+end

lib/runner.ex

@@ -15,6 +15,7 @@ defmodule Runner do
     Processes,
     Tasks,
     Agents,
+	Integers,
   ]
 
   def koan?(koan), do: Enum.member?(@modules, koan)

test/koans/integer_koans_test.exs

@@ -0,0 +1,17 @@
+defmodule IntegerTests do
+  use ExUnit.Case
+  import TestHarness
+
+  test "Integers" do
+    answers = [
+      true,
+      false,
+      [5, 8, 1, 2, 7],
+      1234,
+      '7',
+      "1234",
+    ]
+
+    test_all(Integers, answers)
+  end
+end