added db:drop task that executes mysql:drop_databses and postgresql:drop_databases

activerecord/Rakefile

@@ -41,6 +41,7 @@ end
 
 namespace :db do
   task :create => ['mysql:build_databases', 'postgresql:build_databases']
+  task :drop => ['mysql:drop_databases', 'postgresql:drop_databases']
 end
 
 %w( mysql mysql2 postgresql sqlite3 sqlite3_mem firebird db2 oracle sybase openbase frontbase jdbcmysql jdbcpostgresql jdbcsqlite3 jdbcderby jdbch2 jdbchsqldb ).each do |adapter|