Auto-versioning builds for PHP & Bower

Summary Change PHP and Bower package creation behavior to follow the Gemfury standard of always building a single package from the tip of the git push-ed master branch. Customers will still have the option to version packages explicitly or tag-based, where the package version will be created based on the SemVer-compatible Git tags. Motivation Since implementing support for PHP and Bower, we and our customers have identified the following deficiencies with the current implementation of the Composer and Bower package builder: