Remove DelegateContext
Make the currently executing context public
Allow role identifiers to lack any implementation
Module that uses method_missing to delegate calls to other Modules

Expects DCI::Context.current to respond to [] for the "other Modules"
Apply roles using Castable
Allow use case triggers to lack any implementation
Make most Context methods private
Add README
Move constant-to-role magic to a separate module
Make Context a module
Merge branch 'module-include'

Fixes GH-2
Version 0.0.2