Build Time Optimization for i18n

[kitsonk]

Somewhat dependent on #53, this issue it to propose how any resource bundles can be build optimized. There are clearly two concepts, we need a mechanism to have n number of language/region codes to be statically resolved at build time and bundled into a distributable. We also still need to be able to resolve non-bundled region codes and allow them to be loaded at run-time.

[rishson]

@mwistrand tracking this as refs dojo/cli-build-webpack#30 - please track you work there.

[dylans]

dojo/cli-build-webpack#30 was also resolved, so this should have been closed.