check_smart

• Show drive(s) causing the UNKNOWN status when checking multiple drives using -g / --global parameter #89
• Add possibility to hide the drive's serial number in the plugin output using --hide-sn #90
• Check (by default) for high Load Cycle Count of hard drive. Can be ignored using --skip-load-cycles parameter #91

• Allow skip temperature check, introduces new parameter --skip-temp-check
• Improved handling of missing or non-executable smartctl command

Bugfix when interface parameter was missing in combination with -g (#79)