More onboarding improvements (#83)

* Improved custom YYYY-MM-DD output template option

* Clarified embedding vs. downloading on media profile form

* Improved form helpers more; Added a helper to every field

lib/pinchflat/downloading/output_path_builder.ex

@@ -40,7 +40,7 @@ defmodule Pinchflat.Downloading.OutputPathBuilder do
       "upload_year" => "%(upload_date>%Y)S",
       "upload_month" => "%(upload_date>%m)S",
       "upload_day" => "%(upload_date>%d)S",
-      "upload_yyyy_mm_dd" => "%(upload_date>%Y)S-%(upload_date>%m)S-%(upload_date>%d)S"
+      "upload_yyyy_mm_dd" => "%(upload_date>%Y-%m-%d)S"
     }
   end
 end