Fixes for Rails 4.0

Here's a patch of fixes that make this work with Rails 4.0. The main thing I changed was the way the versions get checked... I didn't want to make the logic say:

```ruby
if rails31? || rails32? || rails40?
```

in a bunch of places, so I changed those accessors to have a few different variations of:

```
rails_31_or_above?
```

as was appropriate to solve all of the various cases. Other than that, there were a few small cases of code having changed namespaces or things being deprecated.