Add a new (failing) feature test to show the behavior I think would be good for the "ignore" helper.

These scenarios show ignoring files by their source paths rather than their output paths,
ignoring globbed paths (including into subdirectories), and ignoring paths that will be transformed
by directory_indexes. These scenarios pertain to issues #229 and #225.

middleman-core/features/ignore.feature

@@ -0,0 +1,50 @@
+Feature: Ignoring paths
+  Scenario: Ignore a single path
+    Given a fixture app "ignore-app"
+    And a file named "config.rb" with:
+      """
+      ignore 'about.html.erb'
+      ignore 'plain.html'
+      """
+    And a successfully built app at "ignore-app"
+    Then the following files should exist:
+      | build/index.html |
+    And the following files should not exist:
+      | build/plain.html |
+      | build/about.html |
+
+  Scenario: Ignore a globbed path    
+    Given a fixture app "ignore-app"
+    And a file named "config.rb" with:
+      """
+      ignore '*.erb'
+      ignore 'reports/*'
+      ignore 'images/**/*.png'
+      """
+    And a successfully built app at "ignore-app"
+    Then the following files should exist:
+      | build/plain.html |
+      | build/images/portrait.jpg |
+    And the following files should not exist:
+      | build/about.html |
+      | build/index.html |
+      | build/reports/index.html |
+      | build/reports/another.html |
+      | build/images/pic.png |
+      | build/images/icons/messages.png |
+
+  Scenario: Ignore with directory indexes
+    Given a fixture app "ignore-app"
+    And a file named "config.rb" with:
+      """
+      activate :directory_indexes
+      ignore 'about.html.erb'
+      ignore 'plain.html'
+      """
+    And a successfully built app at "ignore-app"
+    Then the following files should exist:
+      | build/index.html |
+    And the following files should not exist:
+      | build/about/index.html |
+      | build/plain/index.html |
+

middleman-core/fixtures/ignore-app/config.rb

@@ -1,2 +0,0 @@
-page "/my_article.html", :proxy => "/template.html", :ignore => true, :layout => false
-page "/articles/my_article.html", :proxy => "/articles/template.html", :ignore => true, :layout => false

middleman-core/fixtures/ignore-app/source/articles/template.html.erb

@@ -1 +0,0 @@
-<%= [1,2,3].join("-") %>

middleman-core/fixtures/ignore-app/source/template.html.erb

@@ -1 +0,0 @@
-<%= [1,2,3].join("-") %>