commit 9ad4104dc6970b8ed9ae6660912d51355146cbe1
author Marc Kriguer <myk@google.com> Thu Dec 12 10:38:40 2013 -0800
committer Marc Kriguer <myk@google.com> Fri Dec 13 14:19:57 2013 -0800
tree 79c2ff781a8e80207d8f199d52d96cc360f38704
parent 67871c45adc51dd1dc8c1f7b5d6047df51d31618

Allow either user or password to be overridden

Current behavior:
* Default user and default password must be specified;
* Overriding both user and password for a given server is allowed;
* Overriding just the password for a given server is allowed;
* Overriding just the user for a given server gives an error.

New behavior:
* Default user and default password no longer needed.
* If a per-server user and/or password is specified, use it
  (otherwise, use the default).
* If the user and/or password is non-empty, throw the exception.