Use a submodule for Haystack

Hi Rodolphe,

Now I understand how you want to deploy Lolyx. Sorry if I bombarded you with questions (they might have seemed stupid in the abtsract).

When I said “what is haystack ? It looks like something that shouldn't have been committed” in #6, it's because I deploy using virtual environments and `requirements.txt` files. I did know what it was, I meant “why aren't you just putting it in your `requirements.txt`.”

I understand you only want to use debian packages to deploy `lolyx` repo. And you want it to be self contained.

Therefore, I do think we should use a submodule for haystack and other third-party apps.

 * First of all, this way we track the changes on haystack files.
 * On another hand, it allows us to document and easily pin a specific version of haystack.

For example, with my pull request, if I run:

```
$ cd haystack/
$ git show
commit 82c9fa029a652b03c8ae1b2db24a5ab2ea1b629b (HEAD, tag: v2.1.0)
Author: Daniel Lindsley <daniel@toastdriven.com>
Date:   Sun Jul 28 14:36:57 2013 -0700

    Bumped to v2.1.0!
```

I can see we are using Haystack 2.1.0. I can also do:
```
$ cd haystack/
$ git checkout v1.2.7
Previous HEAD position was 82c9fa0... Bumped to v2.1.0!
HEAD is now at 231f41f... Bumped to v1.2.7!
$ cd ..
$ git add haystack/
$ git commit -m "Rollback haystack to v1.2.7"
```

What do you think?

Other question (unrelated), why are we maintaining this *franco-français* project in English?