compile failure for pre-AMP base

With e.g. GHC 7.8.4 / base-4.7:

```
Configuring component lib from users-0.5.0.0...
Preprocessing library users-0.5.0.0...
[1 of 1] Compiling Web.Users.Types ( src/Web/Users/Types.hs, /tmp/matrix-worker/1496510702/dist-newstyle/build/x86_64-linux/ghc-7.8.4/users-0.5.0.0/build/Web/Users/Types.o )

src/Web/Users/Types.hs:204:18: Not in scope: ‘<$>’

src/Web/Users/Types.hs:205:18: Not in scope: ‘<*>’

src/Web/Users/Types.hs:206:18: Not in scope: ‘<*>’

src/Web/Users/Types.hs:206:37: Not in scope: ‘<$>’

src/Web/Users/Types.hs:207:18: Not in scope: ‘<*>’
```

I've already corrected the meta-data for the affected releases at

- https://hackage.haskell.org/package/users-0.5.0.0/revisions
- https://hackage.haskell.org/package/users-0.4.0.0/revisions

There is no need to upload a new release just for the meta-data.