Nbcelltests

- Test and lint object 27
- Linter cleanup
- Packaging cleanups
- Py3.6+
- Windows path fixes
- Better parsing (uses AST rather than string parsing)
- Autopep
- Kernel checks

- Lint returns objects
- Better dist
- Raw reports/json
- Better docs

- Write cell tests from the browser
- Extract and run cell tests as unittests
- Run tests and view results from browser