Relax constraints for wiki slug

Since GitHub doesn’t apply these constraints to theirs wiki slug
allowing characters like `,`, `:`, `*`, etc, we need to relax our
constraints or some wiki pages will not be available after they were
imported.

For an example the Devise project have a wiki page with the following
slug: “How To: Add sign_in, sign_out, and sign_up links to your layout
template”

app/models/wiki_page.rb

@@ -169,7 +169,7 @@ class WikiPage
   private
 
   def set_attributes
-    attributes[:slug] = @page.escaped_url_path
+    attributes[:slug] = @page.url_path
     attributes[:title] = @page.title
     attributes[:format] = @page.format
   end

app/views/projects/wikis/_new.html.haml

@@ -5,12 +5,9 @@
         %a.close{href: "#", "data-dismiss" => "modal"} ×
         %h3.page-title New Wiki Page
       .modal-body
+        .form-group
           = label_tag :new_wiki_path do
             %span Page slug
           = text_field_tag :new_wiki_path, nil, placeholder: 'how-to-setup', class: 'form-control', required: true, :'data-wikis-path' => namespace_project_wikis_path(@project.namespace, @project)
-        %p.hidden.text-danger{data: { error: "slug" }}
-          The page slug is invalid. Please don't use characters other then: a-z 0-9 _ - and /
-        %p.hint
-          Please don't use spaces.
         .form-actions
           = link_to 'Create Page', '#', class: 'build-new-wiki btn btn-create'

config/routes.rb

@@ -513,7 +513,7 @@ Rails.application.routes.draw do
           end
         end
 
-        WIKI_SLUG_ID = { id: /[a-zA-Z.0-9_\-\/]+/ } unless defined? WIKI_SLUG_ID
+        WIKI_SLUG_ID = { id: /[\S]+/ } unless defined? WIKI_SLUG_ID
 
         scope do
           # Order matters to give priority to these matches

features/project/wiki.feature

@@ -69,11 +69,6 @@ Feature: Project Wiki
     And I click on the "Pages" button
     Then I should see non-escaped link in the pages list
 
-  @javascript
-  Scenario: Creating an invalid new page
-    Given I create a New page with an invalid name
-    Then I should see an error message
-
   @javascript
   Scenario: Edit Wiki page that has a path
     Given I create a New page with paths

features/steps/project/wiki.rb

@@ -132,16 +132,6 @@ class Spinach::Features::ProjectWiki < Spinach::FeatureSteps
     expect(current_path).to include 'one/two/three'
   end
 
-  step 'I create a New page with an invalid name' do
-    click_on 'New Page'
-    fill_in 'Page slug', with: 'invalid name'
-    click_on 'Create Page'
-  end
-
-  step 'I should see an error message' do
-    expect(page).to have_content "The page slug is invalid"
-  end
-
   step 'I should see non-escaped link in the pages list' do
     expect(page).to have_xpath("//a[@href='/#{project.path_with_namespace}/wikis/one/two/three']")
   end