Issue #1741804 by beejeebus, sun, chx, alexpott, matason: Implement a config import/staging directory.
Issue #1668820 by sun, xjm, tim.plunkett, fgm: Concept, base class, and interface for configurable objects.
Issue #1711070 by kid_icarus, tim.plunkett, xjm, droplet, zendoodles and cam8001: Convert tests to use ::$modules property instead of parent::setUp($modules).
Issue #1447686 by sun, beejeebus, Pol, heyrocker, David Strauss: Allow importing and synchronizing configuration when files are updated.
