Add migration to drop invalid OpenGraphCaches, closes #5465

URI.extract recognized http:// as an URL, causing invalid
associations. #5347 already fixed the parsing, this just
cleans up the caches to get rid of the false associations.

db/migrate/20141209041241_drop_open_graph_caches_with_invalid_urls.rb

@@ -0,0 +1,9 @@
+class DropOpenGraphCachesWithInvalidUrls < ActiveRecord::Migration
+  def up
+    OpenGraphCache.where(url: 'http://').delete_all
+  end
+
+  def down
+    raise ActiveRecord::IrreversibleMigration 
+  end
+end

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: 20141024170120) do
+ActiveRecord::Schema.define(version: 20141209041241) do
 
   create_table "account_deletions", force: true do |t|
     t.string   "diaspora_handle"