Restructures the sdk to namespace top-down.

- Changed the esendex module to be the top of the tree.
- Added core to be the centre of the module star.
- Added config to allow namespace-scoped credentials.
- Updated sample to work with the new architecture.
Added missing core test for dispatcher integration.
Fixed an incorrect test name for config test.
Merge pull request #1 from Codesleuth/Restructuring

Restructuring