Does not perform 'deploy:pending:log' at the first time to deploy.

At the first time to deploy with capistrano-pending, 'deploy:pending:log' tries to get the revision of an application already been deployed but it will fails. 

The failure is caused by the assumption of `capistrano-pending`, an application has been already deployed without `capistrano-pending` before. 

The first deploy would work if this pull request was merged :sushi: