Allow BitButcket AWS CodeDeploy add-on to send single commit. (BB-15843)

The BitBucket AWS CodeDeploy add-on is a great way to deploy a project to AWS, but during testing I have discovered that it always deploys the entire project. For large web-sites this will not be acceptable. Ideally the Deploy to AWS link should differentiate between a "branch" and a "commit" so it can send the entire "branch" or only the changes contained in the "commit".

Without this ability, a single change to a single page on a very large web-site requires all pages, files, images, etc to be updated on all servers.