Change "root" route to "blog_root" to avoid name clash with applications's "root" route

If you're using

    config.inline_main_app_named_routes = true

which you probably want if you add blogit to your existing rails app, then a link in the nab to root got overridden by Blogit::Engine to "/blog" (or whatever you set it to be in your app's routes.rb). That's imho no way to go, because I want links to home page to still point to /.

This patch let's you keep on using root for your home page and adds blog_root to entry point for blogit.

Unfortunately I'm not able to run the tests (via rspec) because of database errors I'm not familiar with.