ExtensionMethods.ToCredentialsFromUri would always return null

The method ExtensionMethods.ToCredentialsFromUri would always return
null because it was telling string.Split to only return 1 value.

Once that bug was fixed, it would cause units tests to fail because the
IChangeTrackerClient (specifically Puller) would not always have an
HttpClient.  Added an additional null check to ChangeTracker.
Project changes to get running locally.