[Bug] Don't use ].DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken) in samples/templates

[jmprieur]

In the templates and dev samples, don't use

[httpClient].DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);

but rather create a HttpRequestMessage and add the header tot he request.

https://github.com/AzureAD/microsoft-identity-web/search?q=DefaultRequestHeaders.Authorization&unscoped_q=DefaultRequestHeaders.Authorization

[pmaytak]

Included in Microsoft Identity Web 0.2.1-preview release.