Add documentation

- Document measurements validation.
- Document conversion factors.
- Document datasets API
Merge pull request #166 from MastodonC/feature/docs

Feature/docs
Update documentation link.
Merge pull request #167 from MastodonC/feature/doc-link

Update documentation link.
First attempt insert/get tests.
Bump schema_gen dependency.
Add sensor test and full test.
Added cleanup method.
Change to deftest.
Add test selector.
Removed atoms.
Working tests with a use-fixture.

Added a log statement inside the use-fixture to verify that it is being run as apposed to just the tests.
Merge branch 'feature/data-tests' of github.com:MastodonC/kixi.hecuba into feature/data-tests