Add translate for "Not editable" node 

Hello,
There is a message for the not editable node, this one is not translatable. So I modified the line 216 to translate this.
Regards,
Message not editable translatable.

Make the a message for the not editable node translatable.
Add translation for this message in en and fr
Merge branch 'patch-2' of https://github.com/vignolet/SonataDoctrinePhpcrAdminBundle into vignolet-patch-2

Conflicts:
	Resources/translations/SonataDoctrinePHPCRAdmin.fr.xliff
add a german translation too