Multinode TestFramework logs

[cytadela8]

Currently there is no way (I don't know any way) to access logs of nodes created by multinode tests. If there are any problems (like in PR #794) it's very hard to debug.

We should make it so there are some log files created. Log files should contain all exceptions thrown by nodes. Creation of log files should be optional.

[cytadela8]

I found a bug in config that prevented creation of logs at all. I made this small change to fix that. Probably we should make some more complex solution as all nodes write to one file now.