`build (minBound :: Int)` renders as "-0"

We're using text-format-0.3.1.1

```
Data.Text.Buildable Prelude> build (minBound :: Int)
"-0"
```

`Integer` is also affected which is a weirder/worse case:

```
Data.Text.Buildable Prelude> build (-9223372036854775807 :: Integer)
"-9223372036854775807"
Data.Text.Buildable Prelude> build (-9223372036854775808 :: Integer)
"-0"
Data.Text.Buildable Prelude> build (-9223372036854775809 :: Integer)
"-9223372036854775809"
```

The bug is [here](https://github.com/bos/text-format/blob/master/Data/Text/Format/Int.hs#L54):

```
decimal i
| i < 0 = minus <> go (-i) --- < HERE
| otherwise = go i
where
go n | n < 10 = digit n
| otherwise = go (n `quot` 10) <> digit (n `rem` 10)
```

Since `negate minBound` is not representable. In fact I wrote this bug myself a couple weeks ago :) . Will submit a little PR shortly.