Adding first cut of Redactions support

Redactions support hiding historical versions of elements and
collecting meta-data about that action together.

test/unit/redaction_test.rb

@@ -0,0 +1,36 @@
+require File.dirname(__FILE__) + '/../test_helper'
+require 'osm'
+
+class RedactionTest < ActiveSupport::TestCase
+  api_fixtures
+  fixtures :redactions
+
+  def test_cannot_redact_current
+    n = current_nodes(:node_with_versions)
+    r = redactions(:example)
+    assert_equal(false, n.redacted?, "Expected node to not be redacted already.")
+    assert_raise(OSM::APICannotRedactError) do
+      n.redact!(r)
+    end
+  end
+
+  def test_cannot_redact_current_via_old
+    n = nodes(:node_with_versions_v4)
+    r = redactions(:example)
+    assert_equal(false, n.redacted?, "Expected node to not be redacted already.")
+    assert_raise(OSM::APICannotRedactError) do
+      n.redact!(r)
+    end
+  end
+
+  def test_can_redact_old
+    n = nodes(:node_with_versions_v3)
+    r = redactions(:example)
+    assert_equal(false, n.redacted?, "Expected node to not be redacted already.")
+    assert_nothing_raised(OSM::APICannotRedactError) do
+      n.redact!(r)
+    end
+    assert_equal(true, n.redacted?, "Expected node to be redacted after redact! call.")
+  end
+
+end