Simplify Authentication for Vanilla OpenStack

[carolynvs]

When writing integration tests against vanilla OpenStack, two usability concerns jumped out at me:

First, that I had to specify the identity twice (see example below) as it wasn't using the identity provider's default identity.

var identity = new CloudIdentity{ Username= "{username}", Password= "{password}" };
var identityProvider = new OpenStackIdentityProvider("{identity-url}", identity);

// before, passing null would cause an exception because the default identity wasn't used
var userAccess = identityProvider.Authenticate(identity);

// after
var userAccess = identityProvider.Authenticate();

Second, when authenticating, if both the project/tenant name and project/tenant id wasn't provided, an exception was thrown. The project/tenant id is now optional (see example below), as that seemed a bit redundant.

var identity = new CloudIdentityWithProject
    {
        Username = "{username}",
        Password = "{password}",
        ProjectName = "{project}"
    };

The integration test configuration has been updated to use vanilla OpenStack instead of Rackspace. In order to run the tests, you must have the following environment variables set:

• OPENSTACKNET_IDENTITY_URL - The url to the identity endpoint
• OPENSTACKNET_USER - The user name
• OPENSTACKNET_PASSWORD - The user password
• OPENSTACKNET_PROJECT - The project name