enable tests to use http and https, fix https issue

* forcing source code level 1.6
* using JUnit's @Parameterized capabilities all tests are executed twice: once for http://localhost:7473 and https://localhost:7472
* RestTestBase builds up its own keystore for https tests to match the one from the Neo4j server
* neo4j-server.properties amended with SSL configuration
* BatchRestAPITest/BatchRestAPITransactionTest: skip https tests until https://github.com/neo4j/neo4j/pull/891 has been merged
* EmptyGraphTest: make sure a new DB gets started in teardown
* Neo4jDatabaseCleaner: deal gracefully if referenceNode is not existing
* RestAutoIndexTest: fix test isolation by resetting autoindex setup
* RestTestBase: make sure keystore is only initialzed once
* pathOrAbsolute did not work if a https url was passed in as path