Ignore IntelliJ IDE generated files.
Bumping Neo4j version to 1.9.M04 to conform with Blueprints.

- It seems that Neo4j tests (by generating Impermanent DB) consumes much
more memory and causes OutOfMemory exceptions, this patch increases the memory size (to 1GB)
for the execution of surefire plugin.
- The patch also uses Neo4j's standard way to build an Impermanent graph
via factory instead of initiating it directly.