Fix the generated Junit code.

[UrsZeidler]

Currently the generated junit code contains a minor error.
In the createFixture() method the compiled contract can no longer get via ethereum facade.

We need to add a method in the AbstractContractTest as following:

public CompiledContract getCompiledContract() throws InterruptedException, ExecutionException {
	Map<String, CompiledContract> map = ethereum.compile(contractSource).get();
	return map.get(getContractName());
}

And use this method in createFixture().