Social media buttons on item page

This branch adds social media buttons to item page. They might not look that great yet but should work for now. Don't know about the email button, but I think facebook and twitter buttons are not supposed to work correctly when running the app locally. New tab to facebook/twitter page should open, but you shouldn't be able to actually share anything yet, because facebook/twitter doesn't consider the localhost link as valid. So I think that we'll see if it works only when it is deployed.