Remove email observer specs

Signed-off-by: Dmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

spec/observers/email_observer_spec.rb

-require 'spec_helper'
-
-describe EmailObserver do
-  let(:email)      { create(:email) }
-
-  before { subject.stub(notification: double('NotificationService').as_null_object) }
-
-  subject { EmailObserver.instance }
-
-  describe '#after_create' do
-    it 'trigger notification to send emails' do
-      subject.should_receive(:notification)
-
-      subject.after_create(email)
-    end
-  end
-end