Publish notification when adding user

[PVince81]

Fixes #4

• Will require Preliminary frontend work #13 to be able to fix the links.

[PVince81]

• discard/kill that notification if the user membership was removed before the notification is shown or the group was deleted

[PVince81]

• BUG: router doesn't return correct link

[PVince81]

Ready for review @jvillafanez @DeepDiver1975 @IljaN @VicDeo

I'll investigate how to kill the notification in case of deletion separately, seems to be tricky.

[DeepDiver1975]

cries for info.xml enhancement ....

[PVince81]

if we had a generic service registration we wouldn't need to enhance core for everything out there

<services><service type="\OC\INotifier">\OCA\CustomGroups\Notifier</service></services>

then core (or any app) could just find all services of a given type/namespace.

That was what I hoped to achieve with https://central.owncloud.org/t/service-based-app-imlpementation-to-solve-inter-app-dependencies/1615

[DeepDiver1975]

use ?

[PVince81]

I could... but I somehow hate having IManager without knowing what a "manager" is.
This should have been called INotificationManager in the first place.

Or I could use use xxx as yyy ?

[DeepDiver1975]

parent:setup?

[DeepDiver1975]

mock?

[PVince81]

I don't want to mock it... too many calls to it and in the end the default one works fine as it will return the same texts untranslated but formatted

[PVince81]

@DeepDiver1975 fixed the namespace use and added parent::setUp.

Other pieces aren't blockers from my POV.