Add Support for re-authentication of the access-token with Google

[drbobbeaty]

We needed to have the ability to re-authenticate (renew) an access-token from an initial call to get-access-token when the token timed out. In order to do this, there needed to be a few additions to the endpoint map to hold the query parameters for Google to generate a refresh-token, and then we had to add the function to actually call the service to generate a new token.

At the same time, I added an example for Google usage, as that's what we're using, so that the next guy won't have to do all this work that I needed to do to figure out how to get Google OAuth2 working.