Instead of asserting that openstacksdk created a logging file,
we read the contents of that log file now. The benefit is, that
this integration test gives users an idea how to actually use the
logging feature and also read the contents of the log file.

Change-Id: I9e3c75dda4c1c920937c9780fbdcbe3caeb4d6ad

The solution is based on implementation of logging option
in Open Telekom Cloud collections.

Change-Id: Ie8b309d2aaa8da57794888848fc5414de207e54f