Setup doesn't respect user provided database information

[cullenlinn]

During the last commit when the DashboardController and DashboardModel were refactored for DI, the logic to merge the post input with the config was lost and now only the json config database information is respected.

This can be reproduced by doing a net new installation of the app and supplying custom database information.

One fix is to perform the config and input merging in the controller's updateDatabase method. I confirmed that this approach corrects the issue.