Adds support for master branch deprecation in favor of 'production'

The primary change, and the reason for the major version number update, is that the old version of these scripts relies on the "live" branch being called "master". The updates here change this, so that the "live" branch is now configurable, and defaults to "production". When updating to this release, you should:

• Branch off your "master" branch to a new branch called "production" (or what you will)
• Use composer to pull in this release.
• run robo configure --prod-branch=production
• Edit your .circleci/config.yml and update the robo configure line to include --prod-branch=production
• Delete your "master" branch.