move app staging conditionals around

Change-Id: Id23fd6d50ac1077be014eccddf19adef1c265ef7
add AppStager.stage_app_async to be used with streaming staging logs

Change-Id: Idba41d3ec7af4a61fd34a08e3014e357a000df17
made AppStager.staging_request specs a bit better

Change-Id: Ia33d7d1b821655262cf266b955d077e2b252f129