Keep up with changes to Kuha Document Store

[cessda-bitbucket-importer]

Original report on BitBucket by Toni Sissala (GitHub: toni-sissala).

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API in DocumentStoreDatabase has changed in latest master of Kuha Document Store.

Require latest commit of Kuha Document Store master and change CDCAggDatabase class (subclass of DocumentStoreDatabase) accordingly. Make sure there are tests that ensure subclass and parent work nicely together.

[cessda-bitbucket-importer]

Original comment by Toni Sissala (GitHub: toni-sissala).

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Merged in feature/14-keep-up-with-changes-to-kuha (pull request #20)

Keep up with changes to Kuha Document Store & Kuha Common

Require latest master of Kuha Document Store.

DocumentStoreDatabase API has changed in latest master of Kuha
Document Store. Implement CDCAggDatabase._prepare_validation_schema(),
which sets the validation schema for Study record.

Add tests to ensure validation is correctly loaded on record INSERT
and UPDATE.

Require latest commit of Kuha Common master

Latest Kuha Common has changes in HTTP response bodies that are
results of HTTPErrors.

Bump version to 0.2.0

Write unreleased changelog entry for 0.2.0

Fixes #14 at Bitbucket