Issues with dependencies

Hello!

I'd like to play with QuickFuzz, but have problems building it. Since I'm not familiar with Haskell and stack, I wonder if you could help to resolve the issue:

```bash
$ stack install --flag QuickFuzz:image
Didn't see language-go-0.9 in your package indices.
Updating and trying again.
Selected mirror https://s3.amazonaws.com/hackage.fpcomplete.com/
Downloading timestamp
No updates to your package index were found
Update complete
The following package identifiers were not found in your indices: language-go-0.9
Possible candidates: language-go-0.5, language-go-0.6, language-go-0.8, language-go-0.7.
```

I've tried to change the package version to 0.8 in stack.yaml, but another issue has popped up:

```bash
$ stack install --flag QuickFuzz:image
The same package name is used in multiple local packages

global-variables used in:
- PLIndex "global-variables-1.0.1.0"
- PLOther (PLArchive (Archive {archiveUrl = "https://bitbucket.org/jmg/global-variables/get/6bbea1933b8e.zip", archiveSubdirs = ".", archiveHash = Nothing}))

language-go used in:
- PLIndex "language-go-0.8"
- PLOther (PLArchive (Archive {archiveUrl = "https://github.com/remyoudompheng/hs-language-go/archive/master.zip", archiveSubdirs = ".", archiveHash = Nothing}))

```

Thanks in advance!

Inizia da stack.yaml e riproduci il comando segnalato `stack install --flag QuickFuzz:image`. Controlla le dichiarazioni delle dipendenze per verificare la versione non disponibile di language-go e i pacchetti locali duplicati; il lavoro è completato quando il progetto viene compilato senza gli errori segnalati relativi all'indice dei pacchetti o ai pacchetti duplicati.

Scritto dal modello di indicizzazione a partire dal testo della issue.