[Live-demo] Sahana Install - minor edits

[Hamish]

Hamish:
> > this seems less than ideal:
> >
> > -BUILD_DIR=`pwd`
> > +BUILD_DIR="$USER_HOME/gisvm"

Brian:
> that's consistent with quite a few other scripts

is it? none should be relative to $USER_HOME.

what I mean is the build dir should not be installed on the disc, and my
meaning of that variable in this and a few other scripts was specifically
the dir where the build script originates. i.e. `pwd` at the start of the
script & ./bin/ of the svn checkout. maybe a copy of the svn repo ends
up in the home dir, but it tangles the timeline and makes it hard for the
install script to be run outside of the full build process.


cheers,
Hamish