Rails 4

These were the changes I had to make to get Blogit running with a Rails 4 app.

Mostly it's updates to use strong_parameters, but the removal of tagging is obviously a big change. acts_as_taggable_on looked like it would be a bit of a hassle to update and I didn't need tagging for this app. I'd be happy to rebase this branch leaving the (broken) tagging functionality in place if you'd prefer.