Refactoring: Fixed autoloading issues and workarounds by doing dependency requirement the "Rails Way".

- Removed unneeded `require`s
- Replaced needed `require`s with `require_dependency`
- Replaced `load` with Concers
- Kept gem and core `require`s

Read more about ``nrequire_dependency here: http://guides.rubyonrails.org/autoloading_and_reloading_constants.html#require-dependency

Read more about Concerns here: http://api.rubyonrails.org/v5.1/classes/ActiveSupport/Concern.html

app/controllers/application_controller.rb

@@ -1,6 +1,4 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
-require 'exceptions'
-
 class ApplicationController < ActionController::Base
   include ApplicationController::HandlesErrors
   include ApplicationController::HandlesDevices

app/controllers/calendar_subscriptions_controller.rb

@@ -1,7 +1,4 @@
 # Copyright (C) 2012-2015 Zammad Foundation, http://zammad-foundation.org/
-
-require 'icalendar'
-
 class CalendarSubscriptionsController < ApplicationController
   prepend_before_action { authentication_check( { basic_auth_promt: true, permission: 'user_preferences.calendar' } ) }
 

app/controllers/getting_started_controller.rb

@@ -1,7 +1,4 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
-
-require 'resolv'
-
 class GettingStartedController < ApplicationController
 
 =begin

app/controllers/import_zendesk_controller.rb

@@ -1,6 +1,4 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
-require 'zendesk_api'
-
 class ImportZendeskController < ApplicationController
 
   def url_check

app/controllers/integration/ldap_controller.rb

@@ -1,7 +1,7 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
-require 'ldap'
-require 'ldap/user'
-require 'ldap/group'
+require_dependency 'ldap'
+require_dependency 'ldap/user'
+require_dependency 'ldap/group'
 
 class Integration::LdapController < ApplicationController
   include Integration::ImportJobBase

app/controllers/integration/sipgate_controller.rb

@@ -1,5 +1,4 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
-
 require 'builder'
 
 class Integration::SipgateController < ApplicationController

app/controllers/reports_controller.rb

@@ -1,7 +1,4 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
-
-require 'tempfile'
-
 class ReportsController < ApplicationController
   prepend_before_action { authentication_check(permission: 'report') }
 

app/controllers/ticket_overviews_controller.rb

@@ -1,7 +1,4 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
-
-require 'ticket/overviews'
-
 class TicketOverviewsController < ApplicationController
   prepend_before_action :authentication_check
 

app/models/activity_stream.rb

@@ -1,7 +1,5 @@
 # Copyright (C) 2012-2016 Zammad Foundation, http://zammad-foundation.org/
-
 class ActivityStream < ApplicationModel
-  load 'activity_stream/assets.rb'
   include ActivityStream::Assets
 
   self.table_name = 'activity_streams'

app/models/activity_stream/assets.rb

@@ -2,6 +2,7 @@
 
 class ActivityStream
   module Assets
+    extend ActiveSupport::Concern
 
 =begin