Onboarding improvements (#76)

* Disabled pro modal during onboarding

* Restructured the way onboarding changes settings

* Added better upload date template placeholder

lib/pinchflat_web/controllers/media_profiles/media_profile_html.ex

@@ -35,6 +35,7 @@ defmodule PinchflatWeb.MediaProfiles.MediaProfileHTML do
       upload_day: nil,
       upload_month: nil,
       upload_year: nil,
+      upload_yyyy_mm_dd: "the upload date in the format YYYY-MM-DD",
       source_custom_name: "the name of the sources that use this profile",
       source_collection_type: "the collection type of the sources that use this profile. Either 'channel' or 'playlist'"
     }