Moving to `aur` package for AUR interaction

Note that `http-conduit` is being dropped in favour of `wreq`. That also brings `lens` in as a dependency.
I don't have everything installed to check the types but it looks like you want `buildScripts :: FilePath -> IO (Maybe FilePath)`?

If so, what about this?
```haskell
, buildScripts = \fp -> sourceTarball fp name >>= return . fmap decompress
```