如何在Heroku上使用Swaggervel？

I have a Laravel app on Heroku and Swaggervel working on my local machine. The problem occurs when I try to get Swaggervel to work on Heroku.

Here is the 'require' portion of my composer.json:

    "require": {
    "laravel/framework": "5.0.*",
    "jlapp/swaggervel": "dev-laravel5"
    }

as well as the relevant part of app.php:

        'App\Providers\EventServiceProvider',
        'Jlapp\Swaggervel\SwaggervelServiceProvider',
        'App\Providers\RouteServiceProvider',

However, when I try to push my code to heroku using git push heroku dev:master, I get:

remote:          Failed to execute git clone --no-checkout 
'git@github.com:mvpasarel/swagger-laravel.git' 
'/tmp/build_46159f28fecb2012869a3849028ff82c/vendor/jlapp/swaggervel' 
&& cd '/tmp/build_46159f28fecb2012869a3849028ff82c/vendor/jlapp/swaggervel' 
&& git remote add composer 'git@github.com:mvpasarel/swagger-laravel.git' 
&& git fetch composer  

heroku run composer update also works without error. Thanks in advance for any help received :)

EDIT: I have managed to get it to work to some extent. However, the api-docs page looks as follows:

From Guzzle docs (different package but related question):

Bleeding edge

During your development, you can keep up with the latest changes on the master branch by setting the version requirement for Guzzle to ~6.0@dev.

{
   "require": {
      "guzzlehttp/guzzle": "~6.0@dev"
   }
}

You can then change the minimum-stability config as required.

Have you tried "jlapp/swaggervel": "~2.0@dev"?