add showMigration function

Add dbIdColumnsEsc to Sql.Utils. Used in persistent-postgresql 2.1.5.2

• Fix getBy with a primary key. #342

• Break self-referencing cycles in the entity declarations

• Error with Doubles without a decimal part #378
• runSqlPool does not perform timeout checks.

• One extra feature for #939: use logDebugN instead

• Better SQL logging Yesod issue #939

Parse UTCTime in 8601 format #339

Support for monad-control 1.0