Disk space requeriments

The disk space requeriment is too low, or pcbsd uses too much disk
space :)

This is a VBox install.. with a small disk.. 12.2 GB, and default
layout

df:
Filesystem         1K-blocks    Used   Avail Capacity  Mounted on
/dev/label/rootfs0   2031132  504228 1364416    27%    /
devfs                      1       1       0   100%    /dev
/dev/label/usr0      9323828 5391028 3186896    63%    /usr
procfs                     4       4       0   100%    /proc
linprocfs                  4       4       0
100%    /compat/linux/proc

I only have chromium installed as PBI (1 gb or so, stay tuned),
and desktop is lxde + vbox guest.. no more system components

The problem is now I can't upgrade to RC2

- The graphic update manager says: unable to update.. check your
  network connection or mirrors

- The cli one says: you need 6gb free on your usr partition

So the graphic ones shows the wrong error.

And I started with too little disk space to begin with