add period edit form with object extraction
Merge remote-tracking branch 'remotes/smiley/feature/campinfo' into feature/period/edit

Conflicts:
	module/EcampCore/src/EcampCore/Service/PeriodService.php
	module/EcampCore/src/EcampCore/Validation/PeriodFieldset.php
	module/EcampWeb/src/EcampWeb/Controller/Camp/IndexController.php
	module/EcampWeb/src/EcampWeb/Form/PeriodCreateForm.php
	module/EcampWeb/view/ecamp-web/camp/index/editperiod.twig
	module/EcampWeb/view/ecamp-web/camp/index/index.twig