added 'show_gaps' support to the 'kern' graph
added 'show_gaps' support to the 'proc' graph
added 'show_gaps' support to the 'hptemp' graph
added 'show_gaps' support to the 'lmsens' graph
add a check to verify if 'nvidia-smi' command does exists in the system
added 'show_gaps' support to the 'nvidia' graph
added 'show_gaps' support to the 'disk' graph
added 'show_gaps' support to the 'fs' graph