Replace app data after configure rather than merge (#1436)
Replace app data after configure rather than merge (#1436)

Mostly it's equivalent, but the list of placement directives was getting
merged and thus duplicated every time the app was configured.  Replacing
the data rather than merging seems to be the more correct approach.

Fixes #1435
Ubuntu-Solutions-Engineering/conjure,ubuntu/conjure-up,conjure-up/conjure-up,Ubuntu-Solutions-Engineering/conjure,ubuntu/conjure-up,conjure-up/conjure-up