feat(errors): Add migration name for migrate/rollback errors

[robinjoseph08]

if an error occurs during a migration or a rollback, the error is annotated with the name of the migration that caused the error. this makes it easier to debug the source of the error. for example:

$ go run example/*.go migrate
Running batch 1 with 1 migration(s)...
2018/08/23 19:36:52 20180812001528_create_users_table: ERROR #42601 syntax error at or near ")" (addr="[::1]:5432")
exit status 1