reboot the test suite

 - new subproject for integration tests, using ScalaTest 2
 - copy and reïmplement some tests
 - rework some of the samples as tests
 - port examples from Day of Datomic
Merge pull request #87 from pellucidanalytics/topic/reboot-tests

Reboot the test suite
minor: deprecate Props in favor of SchemaEntityBuilder
Merge branch 'develop' as v0.6 release