little improvements for active_model

[Dmitry Gautsel]

Hi all.

What do you think about little improvements listed below?

before:

{ error: message }.merge(options.except(*CALLBACKS_OPTIONS + MESSAGE_OPTIONS))

after:

{ error: message }.merge!(options.except(*CALLBACKS_OPTIONS + MESSAGE_OPTIONS))

before:

matchers.map { |method| method.match(method_name) }.compact

after:

matchers.map! { |method| method.match(method_name) }.tap(&:compact!)

before:

attribute_aliases.merge(new_name.to_s => old_name.to_s)

after:

{new_name.to_s => old_name.to_s}.reverse_merge!(attribute_aliases)

I just started to dive into the Ruby on Rails. And maybe it's not good idea to make this improvements. But if it's OK, I would continue to improve somethign like that.

Regards, Dmitry