Improved the error messaging for the DangerousAttributeError exception

When the DangerousAttributeError exception is thrown, it's not entirely clear where the conflict is originating from.  Now the user is alerted that the conflict is a similarly named column.

I ran into this issue the other day when a column "valid" was added via a migration.  I received the message:

```
valid? is defined by Active Record
```

By the looks of that message, I thought that I had created a method called valid? on my model (which wasn't the case). It took me a while to track down that a column named 'valid' had been added to the table via a migration.