Implement a sonar processor

Hi, 

We've implemented a way for sputnik to run Sonar-runner to report issues.
We use it in conjunction with sonar-ndepend (https://github.com/criteo/sonar-ndepend) but should work with
all sonar plugins as long as they provides the line information.

Cheers
In master I introduced `TestEnvironment` class, which simplifies this to:

``` 
ReviewResult result = processor.process("src/module2/dir/file2.cs");
```