Support any object as extra data when notifying errors

[bagedevimo]

Currently the extra_data support in rollbar-ruby relies on the object being of a specific set of types. This is a bit uncessary, as we do support hashes. So instead of limiting the types by their class name, lets instead check the response to to_h (which always returns hash) and then treat the result as a hash.

This enables support for a larger number of extra_data objects being passed in, including ActiveModel::Errors, the original object that was being passed in at my work.

[waltjones]

@bagedevimo Thank you for the PR. A release is coming up in the next couple days. I'd be happy to merge this change if you can update the hash syntax in the spec.