Remove unused stylesheets.
Bundle update sass, newrelic_rpm and tzinfo gems.

There is a sass-cache related error with the latest version of sass
(3.3.2) that needs to be addressed in sprockets. Not sure if it will,
if it does that means it will be slower to compile in development
environments. For now we can just rely on the latest 3.2.x release.
Set root in same syntax as other config items.
Add items_in_feed config item set to 25.
Update feed view test to paginate based on items_in_feed config.
Add test for feed using a custom number of feed items via config items_in_feed.
Update feed route to use Post.paginate with items_in_feed rather than load all posts.