Checking streams instead of hardcoded folders

Hi there,

I tried to use this plugin to check if I can use Grav CMS on my hosting. I found a problem with permissions of logs directory. I changed the stream for `logs` to a different folder, but sadly Problems Plugin still checks the hardcoded `logs` folder instead of new folder pointed by `logs` stream.

I can think of two possible solution.
1. Create a configuration file with paths
2. Using streams from Grav CMS instead of hardcoded paths

What do you think about this?