Exporer driver test

Testcases for project overview, folder view and file view

Requirements git client: https://github.com/devhub-tud/git-server/pull/26
try to keep the following style:

```java
if (condition) {
    statements;
}
else if (condition) {
    statements;
}
else {
    statements;
}
```

No need to fix now. I think there's an Eclipse formatter in the project root which you can include.