PersonView still visible after logout

[michael-hawker]

Describe the bug

Same issue as microsoftgraph/microsoft-graph-toolkit#142

I tried fixing in similar manner; however, then the Login control's PersonView wasn't working right, very strange.

Steps to Reproduce

Steps to reproduce the behavior:

1. Login to SampleTest app
2. Logout
3. Note user image is erased, but details remain.

Expected behavior

All info should be gone.

Screenshots

If applicable, add screenshots to help explain your problem.

Environment

NuGet Package(s): 

Package Version(s): 

Windows 10 Build Number:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [ ] Insider Build (build number: )

App min and target version:
- [ ] Fall Creators Update (16299)
- [ ] April 2018 Update (17134)
- [ ] October 2018 Update (17763)
- [ ] May 2019 Update (18362)
- [ ] Insider Build (xxxxx)

Device form factor:
- [ ] Desktop
- [ ] Xbox
- [ ] Surface Hub
- [ ] IoT

Visual Studio 
- [ ] 2017 (version: )
- [ ] 2019 (version: ) 
- [ ] 2019 Preview (version: )

Additional context

Add any other context about the problem here.

[Kyaa-dost]

I am consistently seeing the same behavior after testing various times. In my case, the image and data both happened to be there.

[michael-hawker]

Thanks @Kyaa-dost, I had a similar fix that the graph toolkit had in the C# as most of the code is very similar; however, in our case here it introduced another bug, so I decided to log the issue here as a start.