* PayPal TLS Fix
PayPal requires TLS 1.2 now - Added comments explaining this is the
case, and additional error handling for when the callback fails when TLS
1.0 or 1.1 is set.
* Removed Sandbox Credentials
Tch.
* Changed exception to WebException
If the PayPalAuthenticationHandler sees that an error caused by the
wrong SecurityProtocol has occurred, it throws a new WebException
instead of just Exception
* Reverted Whitespace changes to Startup.Auth.cs
Whitespace somehow got changed. I think this reverts it.