Add a new developer command (i.e., requires `HOMEBREW_DEVELOPER` set in
your environment) to "boneyard" a formula, by creating one pull request
removing the formula from its current tap and updating (or creating)
tap_migrations.json, and another pull request importing the formula into
homebrew/boneyard with any bottle block removed.

Closes #53.

Signed-off-by: ilovezfs <ilovezfs@icloud.com>