add activeadmin gem
skipping authenticate_user! before_filter for activeadmin login
running 'rails g active_admin:resource User' and modified app/admin/user.rb file
modified activeadmin user form heading
reverting activeadmin userform to resolve 'ActiveModel::ForbiddenAttributesError'. need to solve soon
add permit_params to solve 'ActiveModel::ForbiddenAttributesError'
 modified/added index and filter part of users in activeadmin
Merge branch 'activeadmin'