Call connection credential callbacks asynchronously on each connection attempt

[mmacfadden]

Versions

• Convergence Version: 1.0.0-rc.8

• Description Presently, you can provide immediate credentials or a call back for credectials. For exmaple

domain.connectWithJwt("myJwt");

or

domain.connectWithJwt(() => getMyJwtReturningAPromise()));

Right now the callback is called only once on the first connect attempt. Especially for things like a JWT the connection might not succeed right away, and could actually complete many minutes from now. Thus, the callback should be called on each connection attempt, when the attempt is being made.