Added Java 9 travis build support

[kaspersorensen]

Truth be told - I haven't yet run this locally. But thought I would let Travis run a Java 9 build while I install it on my local machine too ;-)

[kaspersorensen]

Oh well, seems it doesn't work. Travis fails in bringing up Neo4j:

The command "neo4j-community-2.2.3/bin/neo4j start" failed and exited with 1 during .

And (potentially worse) on my machine, after upgrading to Java 9, I have some issues with the ElasticSearch tests:

org.apache.metamodel.elasticsearch.nativeclient.ElasticSearchDataContextTest  Time elapsed: 0.77 sec  <<< ERROR!
java.lang.ExceptionInInitializerError: null
        at java.management/sun.management.RuntimeImpl.getBootClassPath(RuntimeImpl.java:99)
        at org.elasticsearch.monitor.jvm.JvmInfo.<clinit>(JvmInfo.java:77)
        at org.elasticsearch.node.internal.InternalNode.<init>(InternalNode.java:139)
        at org.elasticsearch.node.NodeBuilder.build(NodeBuilder.java:159)
        at org.elasticsearch.node.NodeBuilder.node(NodeBuilder.java:166)
        at org.apache.metamodel.elasticsearch.nativeclient.utils.EmbeddedElasticsearchServer.<init>(EmbeddedElasticsearchServer.java:52)

[kaspersorensen]

Closing this as I'm not seeing a resolution straight forward.