Only re-download avatar if URL changed (fix #19)

db/schema.rb

@@ -11,7 +11,7 @@
 #
 # It's strongly recommended that you check this file into your version control system.
 
-ActiveRecord::Schema.define(version: 20160316103650) do
+ActiveRecord::Schema.define(version: 20160322193748) do
 
   # These are extensions that must be enabled in order to support this database
   enable_extension "plpgsql"
@@ -40,6 +40,7 @@ ActiveRecord::Schema.define(version: 20160316103650) do
     t.string   "header_content_type"
     t.integer  "header_file_size"
     t.datetime "header_updated_at"
+    t.string   "avatar_remote_url"
   end
 
   add_index "accounts", ["username", "domain"], name: "index_accounts_on_username_and_domain", unique: true, using: :btree