getOption[A] for NULL values

get[A] doesn't support NULLs (and probably shouldn't) -- same idea as List.head and List.headOption. So if you have:

    create table foo (bar text);

You should (since you might get NULL):

    query <- client.prepare("select bar from foo")
    foo <- query.select() { row =>
      val bar = row.getOption[String]("bar")
      ...
    }

Also make None usage symmetrical so you can:

    query <- client.prepare("insert into foo values ($1)")
    foo <- query.exec(None)