cardiff: Computing groups of identical hardware

When running cardiff on a group of servers, we need to understand which
hosts are similar to the others and which ones are different.

cardiff is so computing the differences from several components (disks,
memory, cpu, network). At every step of this check, the groups of
identical are computed to gain at the end a list of servers that are
identical.

A typical output looks like :

[user@hosts]$ cardiff.py -p 'sample/*.hw_'
.....
The 19 systems can be grouped in 3 groups of identical hardware
-> 1 Systems :
CZ3404YWNW
-> 15 Systems :
CZ3404YWP4, CZ3404YWP6, CZ3404YWPP, CZ3404YWP2, CZ3404YWPS, CZ3404YWPX,
CZ3404YWP8, CZ3404YWR0, CZ3404YWPE, CZ3404YWPA, CZ3404YWPC, CZ3404YWPM,
CZ3404YWPV, CZ3404YWPH, CZ3404YWPK
-> 3 Systems :
CZ3404YWNN, CZ3404YWNT, CZ3404YWNR