Tests clean all data from the DB

[dnesteryuk]

After launching tests all data from Neo4j gets removed. Tests must only remove data they create.

[dnesteryuk]

There is a simple workaround which can be used if Docker is used:

$ sudo docker run --name neo4j-test-db -d --env NEO4J_AUTH=none --restart always --publish 7484:7474 neo4j:3.0.6

The launched container will only be used in the test env:

# config/test.exs
config :neo4j_sips, Neo4j,
  url: "http://localhost:7484"

It doesn't solve all problems, but at least the generated data from the dev env doesn't get removed.