[Live-demo] Sahana Install - minor edits

[Hamish]

Brian:
>   the Sahana installl script had two weaknesses; a
> path to install the desktop icon and the delay when starting
> the browser...
> So I have made a minor edit and checked it in.. Please take
> a moment to check, either from svn in a test environment, or
> when the next build is done in about 48 hours..

this seems less than ideal:

-BUILD_DIR=`pwd`
+BUILD_DIR="$USER_HOME/gisvm"



Hamish