[VERSION] bump to v0.6 (dmlc#77)

[VERSION] Bump to v0.5 (dmlc#69)

Prepares for v0.5 release

- Remove the deprecated DLContext
- Updated the comment on kDLCUDAHost to remove remark
  about bit-masking as we cannot introduce future
  enums that depends on this behavior.

[VERSION] Bump to 0.4.0 (dmlc#64)

Update dlpack.h

Update version to keep up with the latest tag

small fix to NEWS.md (dmlc#24)

[BUILD/TEST] Formalize tests, project structure (dmlc#14)

* [BUILD/TEST] Formalize tests, project structure

* update cmake to reflect version