Enhancing manual index support with configuration in GraphML parser.

Hi Alex,

Thanks for your framework, I was happy to find an DBUnit equivalent for Neo4J !

I was stucked on a project where I needed to use Neo4J fulltext index because you can not define the index configuration in xml.
Here is a simple pull-request which allow you to define these index configurations when declaring them.
<index name="myindex" key="mykey" configuration="provider,lucene,type,fulltext">myvalue</index> will create/retrieve an index named 'myindex' with a Map configuration {provider=lucene, type=fulltext}

Regards,
Gautier