changes for additional packages to be packaged from the same build. see BuildParams for example environment variables used to specify the packages and their channels and sourceids. also updated mac packages to use a larger virtual drive and auto-open on download

added default sourceid and check that sourceid is not blank, hoping to get the windows builds to recognize the value

DRTVWR-324 : Suppress the use of BuildParams to set up the channel and use the TC environment settings instead