Refactor roster and initial support for consists

dcc/metadata/admin.py

@@ -1,6 +1,6 @@
 from django.contrib import admin
 from metadata.models import (
-    Decoder, Manufacturer, Company, Tag, RollingStockType)
+    Decoder, Scale, Manufacturer, Company, Tag, RollingStockType)
 
 
 @admin.register(Decoder)
@@ -10,6 +10,12 @@ class DecoderAdmin(admin.ModelAdmin):
     list_filter = ('manufacturer', 'interface')
 
 
+@admin.register(Scale)
+class ScaleAdmin(admin.ModelAdmin):
+    list_display = ('scale', 'ratio', 'gauge')
+    list_filter = ('ratio', 'gauge')
+
+
 @admin.register(Company)
 class CompanyAdmin(admin.ModelAdmin):
     readonly_fields = ('logo_thumbnail',)