free: implement the different size display

[sylvestre]

      -b, --bytes
              Display the amount of memory in bytes.

       -k, --kibi
              Display the amount of memory in kibibytes.  This is the default.

       -m, --mebi
              Display the amount of memory in mebibytes.

       -g, --gibi
              Display the amount of memory in gibibytes.

       --tebi Display the amount of memory in tebibytes.

       --pebi Display the amount of memory in pebibytes.

       --kilo Display the amount of memory in kilobytes. Implies --si.

       --mega Display the amount of memory in megabytes. Implies --si.

       --giga Display the amount of memory in gigabytes. Implies --si.

       --tera Display the amount of memory in terabytes. Implies --si.

       --peta Display the amount of memory in petabytes. Implies --si.

      -h, --human
              Show all output fields automatically scaled to shortest three digit unit  and  dis-
              play the units of print out.  Following units are used.

                B = bytes
                Ki = kibibyte
                Mi = mebibyte
                Gi = gibibyte
                Ti = tebibyte
                Pi = pebibyte

              If  unit  is  missing,  and  you  have  exbibyte  of  RAM or swap, the number is in
              tebibytes and columns might not be aligned with header.

[Krysztal112233]

finished at #35

[cakebaker]

Closing this ticket as everything seems to be implemented, with the exception of --human. I opened a separate ticket for it.