Improved detection on some Nortel switches
Generator.
Get an instance of a logger - correct way; Unused imports removed;
Simplified expression
Merge pull request #504 from vi4m/nortel

Improved detection on some Nortel switches
Merge pull request #505 from andrzej-jankowski/dev

Get an instance of a logger - correct way...
Merge pull request #502 from andrzej-jankowski/master

DISCOVERY - better HITACHI disks detection
discover_network task - minor fix