Update neo4j-java-driver from 1.7.5 to 4.0.1

[michaelweidmann]

Description

This pull request updates the Neo4j Client library to the newest version to support tests with Neo4j 4.X databases and the new neo4j:// URI scheme which provides a much better way to connect to Neo4j databases.

Motivation and Context

This change is required to test Neo4j databases with a version higher than 3 and to test them more reliably with new URI schemes.

How Has This Been Tested?

./gradlew check was successful:

BUILD SUCCESSFUL in 4m 13s
259 actionable tasks: 50 executed, 209 up-to-date

Types of changes

New feature:

• Bumping up the Neo4j Driver version
• Needed to add a license to src/licenses/licenses/reactive-streams/LICENSE because the new version of the library uses reactive streams

Breaking Changes:

• The interface of the library changed so I updated the imports and the classes in the code
• A test used a method which does not exist anymore so I updated the test

Checklist:

• My code follows the [code style][style-guide] of this project.
• I have updated the documentation accordingly.

[michaelweidmann]

I honestly don't know why the Travis CI pipeline crashes...