change credentials on the fly

[toddgeist]

There are cases where we need to override the userName and password supplied by the connection object.

• Authentication Module. Our our authentication module, uses the userName and Password that the user provides to lookup account information. We currently get around this by using fms-js for that connection.
• Basic Auth as an auth mechanism for REST only endpoints. In filemaker land we currently have basic auth as the way to get access to the db and Identify the user. We have a great support for an Authentication feature which allows us to abstract that, away. However that may require somebody adopting more of our system than they want to into their own code. So we should support basic Auth as a way to authenticate.
• Support logging in with different user level access accounts. Currently we have one level of authentication each connection. It might be nice to allow different loggins for different PrivilegeSets

[toddgeist]

If all methods take a param now. And if that param has a auth object on it, it will use that instead of the default credentials for the connection. I think we can have some authBasic middleware that can stick the auth object on the param