Removing upgrade

[Randi Harper]

The way sysinstall handles upgrade is really messy - we have a list of
files that we don't update, and everything else just gets overwritten.
There's bugs in this process (I believe we lose named.conf, among
other thing), and I'm all for pushing users to learn the correct way
to do things, such as freebsd-update. From what I've been reading on
twitter/mailing lists/blog posts, it's mostly new users that are
upgrading through sysinstall. We should update the documentation to
reflect the single easy upgrade path being through freebsd-update
along with detailed instructions on how to do so, if they don't
already exist.

Proposing this patch:

http://deviant.freebsdgirl.com/~randi/sysinstall_no_upgrade.diff

Speak up now against it or forever hold your peace. If this gets
committed, there may be some pushback from the community.

-- randi