Rails4: use link_to instead of hard coded html at ApplicationHelperTest#test_wiki_links_within_local_file_generation_context

On Rails 4.0.2, test fails.

<pre>
  --- expected
  +++ actual
  @@ -1 +1 @@
  -"<p><a href=\"CookBook_documentation.html\" class=\"wiki-page\">documentation</a></p>"
  +"<p><a class=\"wiki-page\" href=\"CookBook_documentation.html\">documentation</a></p>"
</pre>

--HG--
extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012784
replace shoulda context "without workflow privilege" at IssuesControllerTest

--HG--
extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012785
replace shoulda context "with workflow privilege" at IssuesControllerTest

--HG--
extra : convert_revision : svn%3Ae93f8b46-1217-0410-a6f0-8f06a7374b81/trunk%4012786