Update Builder from upstream Make 1.2.1

Complete list of upstream changes from 1.1.1 to 1.2.1 is here:
https://github.com/thethemefoundry/make/compare/1.1.1...1.2.1

This doesn't affect us too much, though now offers the ability to
register other post types to use the builder.
Merge pull request #89 from washingtonstateuniversity/update/make

[PR] Update Builder from upstream Make 1.2.1