KeyError and missing keys in response

As seen in quite a lot of issues (#81, #54, #51, #32), some SSO providers misbehave and either change the response from time to time or return incomplete data.

In some cases this may be overcome by using the scope parameter to request additional scopes (see how to do it).

For example, if you are using Microsoft SSO within your organization, you may require the User.Read.All scope or email scope to get the user's email address.

email was added in 0.8.0 as the default scope for Microsoft SSO.