Implement the register function of OC\ContactsManager
$key is not needed for registering contactsmanager callbacks
Supply the contactsmanager object to the callbacks
camelCase vars in OC\ContactsManager
Merge branch 'master' into contactsmanager-register

Conflicts:
	lib/private/contactsmanager.php
Fix wrong var name
Merge branch 'master' into contactsmanager-register

Conflicts:
	lib/private/contactsmanager.php
no return on register and unregister
Merge pull request #8136 from owncloud/contactsmanager-register

Implement the register function of OC\ContactsManager