Read reports from the config file

So far the `reporting.reports` of the configuration file is ignored.

There is a test that verifies that the configuration is correct in `other/test-configuration.js`
```js
    "when loading files": {
        "when files present": {
           "should use default YAML config when not explicit": function (test) {
                config = configuration.loadFile(undefined, { verbose: true });
                test.equal(false, config.instrumentation.compact());
                test.deepEqual(['lcov', 'cobertura'], config.reporting.reports());
                test.done();
            }
        }
    },
```
but this configuration is never used inside the reporter.

I've added a test, it passes on my machine (Windows) but I'm not sure if I screwed up something else because some tests fails already on Windows.