I have tried to install two different apps for my Salesforce org (MailChimp & EventBrite) and the installation fails because of this error. 
Remoting for Apex Controllers permission is not enabled
CampaignConfirmController: Remoting for Apex Controllers permission is not enabled

How do you enable this?

Is it possible to do bulk record update in my Child Record using Process Builder and Flows Combination ?

My Scenario is - Whenever the Account Owner Changes (in Bulk), the related Contact Owners should be changed. 

Can someone help me how to achieve this using Process Builder and Flows Combination ?