Modify empty project instructions to use double quotes for commit msg.

http://feedback.gitlab.com/forums/176466-general/suggestions/6006904-modify-instruction-to-use-double-quotes-for-windo

app/views/projects/empty.html.haml

@@ -17,7 +17,7 @@
         git init
         touch README
         git add README
-        git commit -m 'first commit'
+        git commit -m "first commit"
         git remote add origin #{ content_tag(:span, default_url_to_repo, class: 'clone')}
         git push -u origin master