Added switch to enable translation of raw devicenames to device mapper names. For instance it will display lv_root for the device /dev/mapper/lv_root instead of dm-0 for the corresponding raw device /dev/dm-0
Merge pull request #754 from tobiaspanknin/tpanknin_show_device_mapper_names_in_iostat_metrics

Added switch to enable translation of raw devicenames to device mapper...