Added OperationNotifications and AmountReached-notification

[dbeuchler]

closes #927

@1nf0rmagician Question: One Amount-Reached notification for all operations (if there is any), or as before, each separately? Does it make sense to have more than one?

[1nf0rmagician]

To make life easy for users I would add the information which order has reached the target amount, i.e. not just "Some order has reached the target amount".

If that is in one notification that is updated on changes or in separate once I don't have a strong opinion on. @dacky179 any opinion on that?

[dacky179]

I think one notification for each single operation is better:

• Code is more easy
• Notifications shown in the Dashboard will be countable. i.e. a combined notification for all would lead to one event shown multiple times in the dashboard: O1 amount reached -> O1 and O2 amount reached -> O2 amount reached.
• for vertical integration it would be nice to have a action when selecting the notification; i.e. like jump to ordermanagement with selected operation to complete. This would be more difficult if its multiple.

[dbeuchler]

Okay, then I will integrate it as before. One Notification for each Operation.