Creating good looking scope hierarchies

* Improved the dev string output of the scope hierarchy to look good. I used `maven dependency:tree` as a model.
* Added a unit test.

```
Root
+- Elder
|  +- ElderElder
|  \- ElderCadet
\- Cadet
```
Merge pull request #25 from square/py/nice_graphs

Creating good looking scope hierarchies