Print errors

[dshinzie-zz]

This is for issue #294. The problem was that Active Record errors are actually from class ActiveModel::Errors instead of ActiveRecord::Base.

• Casting type check was added in method cast_with_active_record in active_record.rb
• New method awesome_active_model_error was added to deal with Active Model Errors
• A marshal_dump was used in order to use a similar column check as method awesome_active_record_instance. The two methods definitely look very similar, but I simply made a new method instead of possibly breaking an existing one
• Since the Error class consists of base, details, and messages, the latter two must be merged into order to make the final Awesome hash

[thiagofm]

Can you please rebase?

[imajes]

@dshinzie: can i convince you to add a quick spec for this too? this is a really worthwhile PR; would love to get it merged into the next release, please!

[imajes]

this is useful so i've pulled in the relevant commits. will look into specs at a later date.

[dshinzie-zz]

nice man!