Add acceptance test for reporting of nested variables

```
root@vagrant:/src/cfengine/core/tests/acceptance/14_reports/00_output# cf-agent -KIf ./report_nested_variable.cf -DAUTO,FAKE_PASS
R: /src/cfengine/core/tests/acceptance/14_reports/00_output/./report_nested_variable.cf Pass
```

```
root@vagrant:/src/cfengine/core/tests/acceptance/14_reports/00_output# cf-agent -KIf ./report_nested_variable.cf -DAUTO
R: /src/cfengine/core/tests/acceptance/14_reports/00_output/./report_nested_variable.cf FAIL
```