Revert "Back-fill tests for MigrateDisk"

This reverts commit 0cfecc3 all the way to b1b9d90

Signed-off-by: Rob Day-Reynolds <rdayreynolds@pivotallabs.com>
Revert "Revert "Add bosh_cli dependency for Bosh::Dev""

This commit brings back the change we wanted to commit, but kept the
accidental commits out.
This reverts commit b1b9d905b0a28f9093ebbfa21b02ac658f0ba90d.