Make Building/Testing commands a package for others in the company who want to bundle and ship shared components #33

Currently the build/dev/test configs sit at the root level of the repo.

We should move these into a package @mindbody/package-bundler (name TBD) so each package can consume this and be more resilient to changes in the repo.

On this line we want to also create a starter package to help others build and test applications @mindbody/app-bundler (name TBD)