MIGRATION: Fix venues latitude/longitude on MySQL.

Before, the schema used a default "decimal" column for these. Unfortunately,
MySQL interprets this as 10 digits, decimal and NO digits, which is crazy.

Now, the schema is 3 digits, decimal and 4 digits.

db/migrate/20120831234448_specify_venues_latitude_and_longitude_precision.rb

@@ -0,0 +1,15 @@
+class SpecifyVenuesLatitudeAndLongitudePrecision < ActiveRecord::Migration
+  FIELDS = %w[latitude longitude].map(&:to_sym)
+
+  def up
+    for field in FIELDS
+      change_column :venues, field, :decimal, :precision => 7, :scale => 4
+    end
+  end
+
+  def down
+    for field in FIELDS
+      change_column :venues, field, :decimal
+    end
+  end
+end