More precise on PHP version
Clearer PHP version requirement
PIM-1460 : add group type controller
PIM-1460 : add navigation and related acl
PIM-1460 : add group type datagrid manager
PIM-1460 : add form type for group type
PIM-1460 : add group type handler and related form
PIM-1460 : add group type routing and views
PIM-1460 : add translated label to group type
PIM-1517 Don't create empty file directories when exporting products without media
PIM-1517 Leave the media field empty in the exported file if there is no media
Beautify some code
Update unit test
PIM-1508 Change the max file size property of attributes to MB
PIM-1460 : add label column
Update behat scenario
Merge branch 'master' of github.com:akeneo/pim-community-dev

Conflicts:
	README.md
Fix error in MediaManager
Fix another error in MediaManager
PIM-1420 : add browse group types scenario