Updated script to allow deployment by branch

Thanks for your interest in bitbucket-sync. With the introduction of the Pipelines feature in BitBucket, this script becomes obsolete and out of scope. The new feature is more flexible, it allows deployment by branch and there is basically no reason not to use it instead of bitbucket-sync. Please see the `readme.md` file for a short description on how to use Pipelines instead of this script. I am going to close this pull request. Thank you!