Direct messages cause notification icons to appear on each team

[jfperusse-bhvr]

I confirm (by marking "x" in the [ ] below):

• [x] This is not a feature idea. Feature ideas go here: http://www.mattermost.org/feature-ideas/
• [x] This is not a troubleshooting question. Troubleshooting questions go here: http://www.mattermost.org/troubleshoot/
• [x] This is a product defect issue that can be reproduced using the steps listed below.
• [x] I have read CONTRIBUTING.md.

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Summary

When receiving a direct message, a red notification icon is added to all tabs and can only be cleared by opening the message on each team.

Steps to reproduce

This is for the Windows Desktop Application version 1.3.0.

• Open the Windows Desktop Application and make sure you have joined more than one team (you should have multiple tabs in the application).
• Ask someone to send you a direct message.

  Expected behavior

The direct message notification icon should be displayed on one team only (e.g. the main team on the server, or make this a user preference), or at least be cleared for all tabs when read on one of the teams.

Observed behavior

The direct message notification icon is displayed on all the teams. The user must open the message in each team for all notification icons to be cleared.

[yuya-oc]

Duplicate of #160.