Add Spinach coverage for Gollum Wiki system and correct the Delete link.

The previously failing Spinach steps have been fixed with this commit.
I have also added new steps that cover the entire usage of the Wiki
system.

The new Spinach steps revealed a minor bug in the Delete page process.
The path for the "Delete this page" button was previously set to
`project_wikis_page(@project, @wiki)` when it should have been
using the singular `project_wiki_page(@project, @wiki)` path helper.

The link has been corrected and all steps are now passing.

features/steps/project/project_wiki.rb

@@ -4,17 +4,73 @@ class ProjectWiki < Spinach::FeatureSteps
   include SharedNote
   include SharedPaths
 
-  Given 'I create Wiki page' do
-    fill_in "Title", :with => 'Test title'
+  Given 'I create the Wiki Home page' do
     fill_in "Content", :with => '[link test](test)'
     click_on "Save"
   end
 
-  Then 'I should see newly created wiki page' do
-    page.should have_content "Test title"
+  Then 'I should see the newly created wiki page' do
+    page.should have_content "Home"
     page.should have_content "link test"
 
     click_link "link test"
     page.should have_content "Editing page"
   end
+
+  Given 'I have an existing Wiki page' do
+    wiki.create_page("existing", "content", :markdown, "first commit")
+    @page = wiki.find_page("existing")
+  end
+
+  And 'I browse to that Wiki page' do
+    visit project_wiki_path(project, @page)
+  end
+
+  And 'I click on the Edit button' do
+    click_on "Edit"
+  end
+
+  And 'I change the content' do
+    fill_in "Content", :with => 'Updated Wiki Content'
+    click_on "Save"
+  end
+
+  Then 'I should see the updated content' do
+    page.should have_content "Updated Wiki Content"
+  end
+
+  And 'That page has two revisions' do
+    @page.update("new content", :markdown, "second commit")
+  end
+
+  And 'I click the History button' do
+    click_on "History"
+  end
+
+  Then 'I should see both revisions' do
+    page.should have_content current_user.name
+    page.should have_content "first commit"
+    page.should have_content "second commit"
+  end
+
+  And 'I click on the "Delete this page" button' do
+    click_on "Delete this page"
+  end
+
+  Then 'The page should be deleted' do
+    page.should have_content "Page was successfully deleted"
+  end
+
+  And 'I click on the "Pages" button' do
+    click_on "Pages"
+  end
+
+  Then 'I should see the existing page in the pages list' do
+    page.should have_content current_user.name
+    page.should have_content @page.title.titleize
+  end
+
+  def wiki
+    @gollum_wiki = GollumWiki.new(project, current_user)
+  end
 end

features/steps/shared/paths.rb

@@ -161,7 +161,7 @@ module SharedPaths
   end
 
   Given "I visit my project's wiki page" do
-    visit project_wiki_path(@project, :index)
+    visit project_wiki_path(@project, :home)
   end
 
   When 'I visit project hooks page' do
@@ -256,7 +256,7 @@ module SharedPaths
   end
 
   Given 'I visit project wiki page' do
-    visit project_wiki_path(@project, :index)
+    visit project_wiki_path(@project, :home)
   end
 
   def root_ref