client = Restforce.new :oauth_token => 'oauth token',
  :instance_url  => 'instance url'

client = Restforce.new :oauth_token => 'oauth token',
  :refresh_token => 'refresh token',
  :instance_url  => 'instance url',
  :client_id     => 'client_id',
  :client_secret => 'client_secret'