inline editing take response from backend

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• 1) do not change event emitter, show error to user to refresh upon rejection from backend
• 2) use observer

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documentation: https://angular.io/docs/ts/latest/cookbook/component-communication.html#!#bidirectional-service

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another easy way to solve this issue is:

• call service directly in the component that is making the change (session component)
• get feedback from the backend in that session
• then emit event to parent using the current approach if sucessful, or show notice to user if failed

in this way, we do not need to change the event emitter to observable

[paradite]

@ZhangYiJiang see comment above is it okay?