* Make datastore tests pass with remote Docker containers
* Make tests consume DOCKER_HOST IP address as bind host while constucting database URI.
This fix makes datastore tests pass against
remote Docker (with host IP different from 127.0.0.1)
Fixes: #586
* Make datastore tests pass on Go1.7.1
* add datastore validator; adapt mock and tests
* adapt bolt datastore to common validator
* adapt postgres datastore to validator
* adapt redis datastore to common validator