Test for partitions with multiple splits

Apply this patch. Run the test. It fails with 

```
java.lang.IllegalStateException: split already set
	at com.google.common.base.Preconditions.checkState(Preconditions.java:176)
	at com.facebook.presto.operator.AbstractScanFilterAndProjectOperator.addSplit(AbstractScanFilterAndProjectOperator.java:93)
	at com.facebook.presto.operator.Driver.processNewSource(Driver.java:251)
	at com.facebook.presto.operator.Driver.processNewSources(Driver.java:216)
	at com.facebook.presto.operator.Driver.access$3(Driver.java:197)
	at com.facebook.presto.operator.Driver$DriverLockResult.close(Driver.java:491)
	at com.facebook.presto.operator.Driver.updateSource(Driver.java:194)
	at com.facebook.presto.testing.LocalQueryRunner.createDrivers(LocalQueryRunner.java:400)
	at com.facebook.presto.testing.LocalQueryRunner.execute(LocalQueryRunner.java:289)
	at com.facebook.presto.testing.LocalQueryRunner.execute(LocalQueryRunner.java:280)
	at com.facebook.presto.TestSimple.testTableHasData(TestSimple.java:66)
```

Set the SPLITS_PER_NODE constant value to 1. Rerun the test. It passes.

The LocalQueryRunner seems to be incapable to deal with partitions that have more than one split.