Fix collections indentation
Added code to generate the full path to the image preview

The image entity can't generate the full path as it doesn't know the location of the web directory.
Added sonata_page_content block to standard_layout.html.twig
Improve getting started documentation: how to use own logo and title
CRUDControllerTest: Added tests for historyAction
Merge pull request #1748 from pulzarraider/crud_controller_history_action_test

CRUDControllerTest: Added tests for historyAction
Added url list type
Merge pull request #1749 from pulzarraider/url_list_type

Added url list type
Merge pull request #1746 from eikes/patch-1

Improve getting started documentation: how to use own logo and title
Deleted duplicate line
Merge pull request #1754 from rkueny/deleted_duplicate_line

Deleted duplicate line
Created AbstractSonataDoctrineAdminExtension - parent class for all SonataDoctrine*Bundles
Updated translations for new keys.
Merge pull request #1757 from ideea/patch-1

Updated translations for new keys.
Merge pull request #1755 from pulzarraider/templates_config_moved_to_sonata_admin

Created AbstractSonataAdminExtension - parent class for all SonataDoctrine*Bundle`s + SonataPropelAdmin extension classes
Update method calls to match changes in BlockBundle
replace get_class per ClassUtils::getClass for entity object
Merge pull request #1567 from KingCrunch/collection-indentation

Extra indentation with collections
Merge pull request #1711 from pulzarraider/sonata_page_content_block

Added sonata_page_content block to standard_layout.html.twig
Added sonata_type_model_hidden form type