Alpha v0.6.0 pre-release

Cleared internal packages - fixes #20 and #21. (#29)

* Fixes #20, #21 issues.

- Moved package /encoding/jsonapi to repository `github.com/neuronlabs/jsonapi` - #20

#21 Changes:
- Removed internal/controller package - moved to /controller
- Removed internal/models package - moved to /mapping
- Removed internal/query, /query/filters, /query/tests packages - moved to /query

Moved /query/mocks to repository `github.com/neuronlabs/neuron-mocks` as a separate repository package.

* Removed readme jsonapi information.