Fixed a test involving writing nicks to csv file.

As the test name suggests, we should test if the nick got written into the csv file by reading and comparing with the csv file itself, not the in-memory representation of the nicks.
Also added a newline to the end of test_nicks.csv file. Because otherwise new nicks are being added as
```
BobNewnick
```
not as
```
Bob
Newnick
```  
Also my editor automagically removed unwanted white spaces. Sorry for that noise.