Update composer.json
Use original class name instead of alias.
Change construction of Statement with a Snak parameter.

In WikibaseDataModel 2.0 it is not directly supported anymore thus wrap it in a
Claim.
Upgrade composer dependencies.
Release notes for 1.3.0
Merge pull request #39 from wmde/upgrade-dm

Upgrade to data-model 2.0 and release
Fix Fix visibility of setUp/tearDown
Merge pull request #40 from wmde/protected

Fix Fix visibility of setUp/tearDown
Update README.md
Update README.md
Reuse existing methods