The Execute engine is being replaced with a filter pattern to enable
further extension of the system, Initiallly a hardcoded filter chain
will be used subsequently to be replaced by a pluggable mechanism.
Loads properties from a file of default properties if found.
the Installer element should define an attribute
loadDefaults with one of the following values.
false - do not look for defaults
prompt - look for properties and ask if they should be used if found
true - look for defaults if found load them
prompt-auto - weird case where installer permits zero user interaction running only from antinstaller-config.xml defaults