Merge pull request #152 from chives/dev-display

Redesigned datagrid action column extensions, Added display element feature
Extracted DataIndexerElement interface
Introduced GenericDeleteElement for clearer method naming
ResourceRepository\Element now extends Admin\ElementInterface
Controllers now require interfaces instead of abstract classes
Display\Element now extends Admin\ElementInterface
Added missing DisplayControllerSpec
Added route_name and additional_parameters options to BatchActionExtension
Redirect old fsi_admin_crud_* routes to new fsi_admin_*
Reorganized templates
Removed PHP 5.3 support, changed apache to built-in web server on travis