A couple of related changes:

First, more down the path of not using a search path
(get it?) when locating files.  Instead, files come from
either a specified location, or from the update server.

Second, the manifest sequence may not be a number in the
future, so start those changes.  This means that this
code can't compare anything other than equality, but
it doesn't actually use it for anything other than a
filename now.  (I tested by setting the sequence to
"sef-test-1".  Found a few problems.  Including a
problem with 0200.run_update.sh, where it wasn't noticing
an error from freenas-install.  Fixed that as well.)
Merge branch 'master' of gitserver.ixsystems.com:/git/repos/freenas-build/freenas