Typo fix s/Ng/ng/
Typo fix s/Ng/ng/

As requested by @jpetitcolas at https://github.com/marmelab/ng-admin/pull/1297#discussion_r97820157
ulrobix/ng-admin,LuckeyHomes/ng-admin,LuckeyHomes/ng-admin,marmelab/ng-admin,marmelab/ng-admin,marmelab/ng-admin,ulrobix/ng-admin,ulrobix/ng-admin,LuckeyHomes/ng-admin