count-objects: add -H option to humanize sizes

Use the new humanize() function to print loose objects size, pack size,
and garbage size in verbose mode, or loose objects size in regular mode.
This patch doesn't change the way anything is displayed when the option
is not used.

Also update the documentation.

Signed-off-by: Antoine Pelisse <apelisse@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-count-objects.txt

@@ -8,7 +8,7 @@ git-count-objects - Count unpacked number of objects and their disk consumption
 SYNOPSIS
 --------
 [verse]
-'git count-objects' [-v]
+'git count-objects' [-v] [-H | --human-readable]
 
 DESCRIPTION
 -----------
@@ -24,11 +24,11 @@ OPTIONS
 +
 count: the number of loose objects
 +
-size: disk space consumed by loose objects, in KiB
+size: disk space consumed by loose objects, in KiB (unless -H is specified)
 +
 in-pack: the number of in-pack objects
 +
-size-pack: disk space consumed by the packs, in KiB
+size-pack: disk space consumed by the packs, in KiB (unless -H is specified)
 +
 prune-packable: the number of loose objects that are also present in
 the packs. These objects could be pruned using `git prune-packed`.
@@ -36,7 +36,13 @@ the packs. These objects could be pruned using `git prune-packed`.
 garbage: the number of files in object database that are not valid
 loose objects nor valid packs
 +
-size-garbage: disk space consumed by garbage files, in KiB
+size-garbage: disk space consumed by garbage files, in KiB (unless -H is
+specified)
+
+-H::
+--human-readable::
+
+Print sizes in human readable format
 
 GIT
 ---