Allow install directory to be specified using "prefix" property.
Allow install directory to be specified using "prefix" property.

cgourlay/nantcontrib,cgourlay/nantcontrib,rmboggs/nantcontrib,dahmage/nantcontrib,nant/nantcontrib,dahmage/nantcontrib,nant/nantcontrib,cgourlay/nantcontrib,dahmage/nantcontrib,nant/nantcontrib,rmboggs/nantcontrib,rmboggs/nantcontrib